Income Taxes - Statutory to Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory tax rate	21.00%	35.00%	35.00%
Low income housing tax credits	(2.50%)	(2.90%)	(3.80%)
Tax-exempt interest	(2.10%)	(4.00%)	(4.40%)
Bank owned life insurance	(0.40%)	(0.80%)	(0.80%)
Gain on sale of a majority interest of insurance business	0.70%	0.00%	0.00%
Other	0.30%	0.30%	0.20%
Impact of the Tax Act	(2.50%)	11.30%	0.00%
Effective Tax Rate	14.50%	38.90%	26.20%