Quarterly report pursuant to Section 13 or 15(d)

Schedule of Total Cash, Cash Equivalents and Restricted Cash (Details)

v3.8.0.1
Schedule of Total Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Cash, Cash Equivalents and Restricted Cash [Abstract]      
Cash and cash equivalents $ 388,450 $ 419,159  
Restricted cash 712,791 635,836  
Total cash, cash equivalents and restricted cash $ 1,101,241 $ 1,054,995 $ 758,916