Mortgage Servicing Rights - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage Banking [Abstract]
Unpaid principal balances	$ 1,350,000	$ 1,400,000
Mortgage Servicing Rights
Estimated fair value of MSR	10,130	11,014	$ 11,401
Estimated future MSR amortization 2017	1,600
Estimated future MSR amortization 2018	1,500
Estimated future MSR amortization 2019	1,300
Estimated future MSR amortization 2020	1,100
Estimated future MSR amortization 2021	1,000
Estimated fair value
Mortgage Servicing Rights
Estimated fair value of MSR	$ 10,100	$ 11,000