Income Taxes Income Taxes (Reconciliation Statutory Income Tax Rates) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent	(5.10%)	(4.20%)	(8.80%)	(4.40%)
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	1.80%	1.70%	1.80%	1.60%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	(2.20%)	0.30%	(2.20%)	(1.20%)
Effective Income Tax Rate Reconciliation, Percent	29.50%	32.80%	25.80%	31.00%