Income Taxes (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Reconciliation of the federal income tax rate to the Company's effective income tax rate        
Federal income tax rate 35.00% 35.00% 35.00% 35.00%
Tax credits, net of equity adjustment (1.00%)      
Permanent differences (1.00%) (1.00%) (1.00%) (1.00%)
Other 2.00%      
Effective income tax rate 35.00% 34.00% 34.00% 34.00%