Income Taxes Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory tax rate	21.00%	35.00%	35.00%
Tax-exempt income	(4.10%)	(6.60%)	(6.50%)
Tax credit investments	(6.10%)	(7.80%)	(7.00%)
Change in valuation allowance	(0.10%)	1.20%	0.30%
Bank owned life insurance	(0.40%)	(0.40%)	(0.60%)
Re-measurement of net deferred tax asset due to the Tax Act	(0.30%)	6.70%	0.00%
State income taxes, net of federal benefit	2.00%	(0.50%)	1.20%
Executive compensation	0.10%	0.10%	0.10%
Other, net	(1.60%)	(1.00%)	(0.10%)
Effective income tax rate	10.50%	26.70%	22.40%