Income Taxes Income Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	$ 37,565	$ 32,506	$ 28,456
Income Tax Reconciliation, State and Local Income Taxes	981	(213)	(1,665)
Income Tax Reconciliation, Tax Exempt Income	(104)	(243)	(571)
Income Tax Reconciliation, Tax Contingencies	(1,159)	(1,377)	(1,776)
Income Tax Reconciliation, Other Adjustments	115	(16)	(91)
Income Tax Expense (Benefit)	$ 37,398	$ 30,657	$ 24,353