Income Taxes (Schedule of Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax expense at Federal statutory rate									$ 18,205	$ 27,174	$ 24,099
Federal statutory rate									21.00%	35.00%	35.00%
(Decrease) increase in taxes resulting from:
Tax-exempt income, net									$ (809)	$ (1,313)	$ (1,599)
Tax-exempt income, net, rate									(0.90%)	(1.70%)	(2.30%)
Dividends received deduction									$ (45)	$ (55)	$ (58)
Dividends received deduction, rate									(0.10%)	(0.10%)	(0.10%)
BOLI									$ (461)	$ (757)	$ (930)
BOLI, rate									(0.50%)	(0.90%)	(1.30%)
Share-based compensation									$ (444)	$ (481)	$ 0
Share-based compensation, rate									(0.50%)	(0.60%)	0.00%
Federal tax credits									$ (364)	$ (364)	$ (364)
Federal tax credits, rate									(0.40%)	(0.50%)	(0.50%)
Change in fair value of contingent consideration									$ (39)	$ (225)	$ (314)
Change in fair value of contingent consideration, rate									(0.10%)	(0.30%)	(0.50%)
State income tax expense, net of federal income tax benefit									$ 2,162	$ 1,411	$ 1,387
State income tax expense, net of federal income tax benefit, rate									2.50%	1.80%	2.00%
Adjustment to net deferred tax assets for enacted changes in federal tax law									$ 0	$ 6,170	$ 0
Adjustment to net deferred tax asset for enacted changes in federal tax law, rate									0.00%	7.90%	0.00%
Other									$ 55	$ 155	$ 152
Other, rate									0.10%	0.20%	0.20%
Total income tax expense	$ 4,523	$ 4,741	$ 4,742	$ 4,254	$ 13,163	$ 6,326	$ 6,505	$ 5,721	$ 18,260	$ 31,715	$ 22,373
Effective tax rate									21.10%	40.80%	32.50%