Stockholders' Equity Schedule of Preferred Dividends Declared (Details) - $ / shares |
3 Months Ended | ||||||
|---|---|---|---|---|---|---|---|
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
|
| Series A Preferred Stock [Member] | |||||||
| Class of Stock [Line Items] | |||||||
| Declaration Date | Sep. 19, 2019 | Jun. 19, 2019 | Mar. 19, 2019 | Dec. 18, 2018 | Sep. 20, 2018 | Jun. 19, 2018 | Mar. 20, 2018 |
| Record Date | Oct. 11, 2019 | Jul. 12, 2019 | Apr. 12, 2019 | Dec. 31, 2018 | Oct. 12, 2018 | Jul. 12, 2018 | Apr. 12, 2018 |
| Payment Date | Oct. 28, 2019 | Jul. 29, 2019 | Apr. 29, 2019 | Jan. 28, 2019 | Oct. 29, 2018 | Jul. 27, 2018 | Apr. 27, 2018 |
| Dividends declared per preferred share (in usd per share) | $ 0.507810 | $ 0.507810 | $ 0.507810 | $ 0.507810 | $ 0.507810 | $ 0.507810 | $ 0.507810 |
| Series B Preferred Stock [Member] | |||||||
| Class of Stock [Line Items] | |||||||
| Declaration Date | Sep. 19, 2019 | Jun. 19, 2019 | Mar. 19, 2019 | Dec. 18, 2018 | Sep. 20, 2018 | Jun. 19, 2018 | Mar. 20, 2018 |
| Record Date | Oct. 11, 2019 | Jul. 12, 2019 | Apr. 12, 2019 | Dec. 31, 2018 | Oct. 12, 2018 | Jul. 12, 2018 | Apr. 12, 2018 |
| Payment Date | Oct. 28, 2019 | Jul. 29, 2019 | Apr. 29, 2019 | Jan. 28, 2019 | Oct. 29, 2018 | Jul. 27, 2018 | Apr. 27, 2018 |
| Dividends declared per preferred share (in usd per share) | $ 0.476560 | $ 0.476560 | $ 0.476560 | $ 0.476560 | $ 0.476560 | $ 0.476560 | $ 0.476560 |
| Series C Preferred Stock [Member] | |||||||
| Class of Stock [Line Items] | |||||||
| Declaration Date | Sep. 19, 2019 | Jun. 19, 2019 | Mar. 19, 2019 | Dec. 18, 2018 | Sep. 20, 2018 | Jun. 19, 2018 | Mar. 20, 2018 |
| Record Date | Oct. 11, 2019 | Jul. 12, 2019 | Apr. 12, 2019 | Dec. 31, 2018 | Oct. 12, 2018 | Jul. 12, 2018 | Apr. 12, 2018 |
| Payment Date | Oct. 28, 2019 | Jul. 29, 2019 | Apr. 29, 2019 | Jan. 28, 2019 | Oct. 29, 2018 | Jul. 27, 2018 | Apr. 27, 2018 |
| Dividends declared per preferred share (in usd per share) | $ 0.453130 | $ 0.453130 | $ 0.453130 | $ 0.453130 | $ 0.453130 | $ 0.453130 | $ 0.453130 |
| Series D Preferred Stock [Member] | |||||||
| Class of Stock [Line Items] | |||||||
| Declaration Date | Sep. 19, 2019 | Jun. 19, 2019 | Mar. 19, 2019 | Dec. 18, 2018 | Sep. 20, 2018 | ||
| Record Date | Oct. 01, 2019 | Jul. 01, 2019 | Apr. 01, 2019 | Dec. 31, 2018 | Oct. 01, 2018 | ||
| Payment Date | Oct. 15, 2019 | Jul. 15, 2019 | Apr. 15, 2019 | Jan. 28, 2019 | Oct. 15, 2018 | ||
| Dividends declared per preferred share (in usd per share) | $ 0.484375 | $ 0.484375 | $ 0.484375 | $ 0.484375 | $ 0.484375 | ||
| Series E Preferred Stock [Member] | |||||||
| Class of Stock [Line Items] | |||||||
| Declaration Date | Sep. 19, 2019 | Jun. 19, 2019 | Mar. 19, 2019 | Dec. 18, 2018 | Sep. 20, 2018 | ||
| Record Date | Oct. 01, 2019 | Jul. 01, 2019 | Apr. 01, 2019 | Dec. 31, 2018 | Oct. 01, 2018 | ||
| Payment Date | Oct. 15, 2019 | Jul. 15, 2019 | Apr. 15, 2019 | Jan. 28, 2019 | Oct. 15, 2018 | ||
| Dividends declared per preferred share (in usd per share) | $ 0.468750 | $ 0.468750 | $ 0.468750 | $ 0.468750 | $ 0.468750 | ||