Noninterest Income - Lending Related Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Lending related fees	$ 41,949	$ 43,265	$ 33,395
Unused commitment fees
Disaggregation of Revenue [Line Items]
Lending related fees	32,452	34,110	25,654
Other
Disaggregation of Revenue [Line Items]
Lending related fees	$ 9,497	$ 9,155	$ 7,741