Quarterly report pursuant to Section 13 or 15(d)

Equity Noncontrolling Interest (Details)

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Equity Noncontrolling Interest (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Jun. 30, 2017
Sep. 30, 2017
Sep. 30, 2016
Jun. 28, 2017
Equity [Abstract]          
Shares of Granite Point Mortgage Trust Inc. common stock received in exchange for contribution (in shares)         33,100,000
Ownership percentage in Granite Point Mortgage Trust Inc.         76.50%
Shares issued by Granite Point Mortgage Trust Inc. in initial public offering (in shares)   10,000,000      
Price per share issued by Granite Point Mortgage Trust Inc. in initial public offering (in usd per share)         $ 19.50
Gross proceeds received by Granite Point Mortgage Trust Inc. in initial public offering   $ 181,900      
Net proceeds received by Granite Point Mortgage Trust Inc. in initial public offering   195,000      
Issuance costs incurred by Granite Point Mortgage Trust Inc. in initial public offering   13,100      
Maximum amount of Granite Point Mortgage Trust Inc. share value that may be purchased by Two Harbors Investment Corp.   $ 20,000      
Acquisition of noncontrolling interests (in shares) 285,662        
Acquisition of noncontrolling interests $ 5,445   $ 5,445 $ 0