Income Taxes (Reconciliation of Statutory and Effective Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Statutory tax rate	21.00%	35.00%	35.00%
Effective tax rate increase (decrease) - State taxes net of federal benefit	2.30%	1.50%	1.20%
Effective tax rate increase (decrease) - Tax-exempt interest	(1.40%)	(2.50%)	(2.40%)
Effective tax rate increase (decrease) - Life insurance	(0.90%)	(1.80%)	(1.90%)
Effective tax rate increase (decrease) - Dividend received deduction	(0.90%)	(1.80%)	(1.80%)
Effective tax rate increase (decrease) - Tax credits	(3.40%)	(4.20%)	(4.40%)
Effective tax rate increase (decrease) - Federal deferred tax revaluation	(1.70%)	(21.70%)
Effective tax rate increase (decrease) - Unrecognized tax benefits, Percent	1.10%	(0.10%)	(0.10%)
Effective tax rate increase (decrease) - Other	0.70%	(2.50%)	(1.50%)
Effective tax rate	16.80%	1.90%	24.10%