Annual report pursuant to Section 13 and 15(d)

Schedule of Related Party Transactions, by Related Party (Details)

v3.10.0.1
Schedule of Related Party Transactions, by Related Party (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Related Party Transaction [Line Items]        
Management fees   $ 30,272 $ 40,472 $ 39,261
Percent per annum of equity used to calculate management fees   1.50%    
Percent per annum of additional equity used to calculate management fees   0.75%    
One Time Downward Adjustment of Management Fees Payable $ 15,000      
Maximum Additional One Time Downward Adjustment of Management Fees Payable $ 3,300      
Compensation costs related to restricted common stock   $ 13,000 11,300 15,200
PRCM Advisers LLC [Member]        
Related Party Transaction [Line Items]        
Management fees   $ 47,800 40,500 39,300
Percent per annum of equity used to calculate management fees   1.50%    
Total One Time Downward Adjustment of Management Fees Payable   $ 17,500    
Direct and allocated costs incurred by manager   $ 26,300 27,900 $ 28,400
Granite Point Mortgage Trust Inc. [Member]        
Related Party Transaction [Line Items]        
Purchases of equity securities of related party (in shares)   1,658,008    
Purchases of equity securities of related party   $ 30,000    
Equity securities, at fair value     29,400  
Equity securities, unrealized gain (loss)     $ (600)  
Proceeds from sales of equity securities of related party   31,200    
Realized gain on sales of equity securities of related party   $ 1,200