Segment Information - Origination Data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Information
Origination Volumes	$ 1,043,715	$ 1,151,944
Loan Sales Data:
Sales margin (fee-based services as a % of loan sales)	1.71%	1.40%
MSR rate (MSR income as a % of loan commitments)	1.88%	1.74%
Structured Business
Segment Information
New loan originations	$ 314,215	$ 145,918
Loan payoffs / paydowns	190,615	190,409
Agency Business
Segment Information
Origination Volumes	1,048,043	1,290,887
Loan Sales Data:
Loan Sales	1,062,437	1,364,850
Fannie Mae | Agency Business
Segment Information
Origination Volumes	662,921	896,549
Loan Sales Data:
Loan Sales	728,395	1,073,347
Freddie Mac | Agency Business
Segment Information
Origination Volumes	308,151	235,032
Loan Sales Data:
Loan Sales	278,516	210,238
FHA | Agency Business
Segment Information
Origination Volumes	60,738	137,936
Loan Sales Data:
Loan Sales	39,293	59,895
CMBS/Conduit | Agency Business
Segment Information
Origination Volumes	16,233	21,370
Loan Sales Data:
Loan Sales	$ 16,233	$ 21,370