Mortgage Banking Operations - Sensitivity Analysis (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Key economic assumptions and the sensitivity of the current fair value for single family MSRs
Fair value of single family MSR	$ 236,621	$ 226,113
Expected weighted-average life	6 years 7 days
Constant prepayment rate (as a percent)	12.94%
Impact on fair value of 25 basis points decrease	$ (17,984)
Impact on fair value of 50 basis points decrease	$ (37,908)
Discount rate (as a percent)	10.40%
Impact on fair value of 100 basis points increase	$ (8,206)
Impact on fair value of 200 basis points increase	$ (15,868)