Derivative Financial Instruments, Agency Business (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) item
Derivative Financial Instruments
Notional Value, classified in Other Assets	$ 292,411		$ 77,984
Notional Value, classified in Other Liabilities	57,850		291,421
Net gains (losses) from changes in the fair value of derivatives	2,600	$ (1,000)
Income from mortgage servicing rights	19,634	$ 20,030
Agency Business
Derivative Financial Instruments
Notional Value, classified in Other Assets	350,261		369,405
Fair Value, classified in Other Assets	2,763		684
Fair Value, classified in Other Liabilities	$ (300)		$ (1,306)
Non-Qualifying | Rate Lock Commitments | Agency Business
Derivative Financial Instruments
Count | item	8		3
Notional Value, classified in Other Assets	$ 34,250		$ 38,578
Fair Value, classified in Other Assets	717		276
Fair Value, classified in Other Liabilities	$ (218)		$ (278)
Non-Qualifying | Forward Sale Commitments | Agency Business
Derivative Financial Instruments
Count | item	63		75
Notional Value, classified in Other Assets	$ 316,011		$ 330,827
Fair Value, classified in Other Assets	2,046		408
Fair Value, classified in Other Liabilities	$ (82)		$ (1,028)