Loan Sales and Servicing - Residential MSRs (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance		$ 49,597
Increase (decrease) in fair value:
Ending balance		53,025
Residential Mortgage
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance		49,597	$ 51,428
Additions		1,543	2,018
Increase (decrease) in fair value:
Due to changes in valuation inputs or assumptions		4,757	346
Due to other changes in fair value	[1]	(2,872)	(3,016)
Ending balance		$ 53,025	$ 50,776

[1] Represents the realization of expected net servicing cash flows, expected borrower repayments and the passage of time.