Federal and state income taxes Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes	40.10%	19.70%	(45.10%)
Effective Income Tax Rate Reconciliation, Tax Contingencies	0.40%	0.20%	32.20%
Effective Income Tax Rate Reconciliation, Nondeductible Expense	6.80%	6.80%	(17.80%)
Effective Income Tax Rate Reconciliation, Tax Credits	(2.00%)	(3.80%)	15.70%
Effective Income Tax Rate Reconciliation, Other Adjustments	0.00%	0.50%	4.30%
Effective Income Tax Rate, Continuing Operations	80.30%	58.40%	24.30%