Income Taxes (Provision For Deferred Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Federal income taxes currently payable									$ 21,015	$ 6,742	$ 2,687
State income taxes currently payable									1,975	288	0
Federal income taxes deferred									11,052	17,422	2,230
State income taxees deferred									2,068	2,850	349
Deferred income tax expense									13,120	20,272	2,579
Provision for income taxes	$ 11,020	$ 5,861	$ 10,889	$ 8,340	$ 8,812	$ 8,045	$ 5,927	$ 4,518	$ 36,110	$ 27,302	$ 5,266