Revenue - Other Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Other operating income (out-of-scope of Topic 606)									$ 31,149	$ 26,256	$ 34,648
Total Other Operating Income	$ 9,735	$ 10,509	$ 9,569	$ 7,533	$ 7,718	$ 8,673	$ 8,314	$ 7,462	37,346	32,167	40,474
Other operating income (in-scope of Topic 606)
Disaggregation of Revenue [Line Items]
Other operating income (in-scope of Topic 606)									6,197	5,911	5,826
Bankcard fees
Disaggregation of Revenue [Line Items]
Other operating income (in-scope of Topic 606)									2,976	2,811	2,597
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Other operating income (in-scope of Topic 606)									1,557	1,508	1,614
Other
Disaggregation of Revenue [Line Items]
Other operating income (in-scope of Topic 606)									$ 1,664	$ 1,592	$ 1,615