Income Taxes (Effective Income Tax Rate Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Federal corporate tax rate									35.00%
Computed “expected” tax on net income									$ 16,493	$ 23,511	$ 13,421
Increase (decrease) resulting from:
Nontaxable interest income									(5,622)	(4,539)	(3,725)
State income taxes, net of federal tax benefit									1,861	3,099	2,056
Nondeductible goodwill and other intangibles									0	0	0
Tax credits									(1,696)	(6,669)	(798)
Valuation allowance									209	1,851	0
Other									(910)	131	(652)
Income tax expense	$ 46	$ 1,492	$ 3,598	$ 5,199	$ (2,258)	$ 6,338	$ 7,032	$ 6,272	$ 10,335	$ 17,384	$ 10,302
Effective tax rates									21.90%	25.90%	26.90%