Income Taxes (Provision For Income Tax Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Abstract]
Current expense									$ 33,116	$ 28,562	$ 12,330
Deferred expense (benefit)									(11,750)	(3,607)	82,297
Tax credits									(6,734)	(6,214)	(5,489)
Tax benefits attributable to items charged to equity and goodwill									2,349	1,250	1,200
Total income tax expense	$ 6,667	$ 6,051	$ (929)	$ 5,193	$ 5,033	$ 7,275	$ 3,329	$ 4,354	$ 16,981	$ 19,991	$ 90,338