Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
U.S. Federal statutory rate	35.00%	[1]	35.00%		35.00%		35.00%
Total provision for income taxes	31.20%	[1],[2]	2.20%	[1],[2]	33.40%	[1],[2]	7.80%	[1],[2]
Percentage the company is obligated to remit to an affiliate of the former significant stockholder					85.00%
Other Tax Expense (Benefit)					$ 4.3
Deferred Other Tax Expense (Benefit)							$ 2.1
Portion Including Payable To Former Stockholder [Member]
U.S. state taxes, net of Federal benefit	(0.60%)	[1]	0.10%	[1]	(0.10%)	[1]	0.80%	[1]
Effective Income Tax Rate Reconciliation, Deductions, Other	(1.60%)	[1]	(2.10%)	[1]	(9.30%)	[1]	(2.20%)	[1]
Effective Income Tax Rate Reconciliation, Revaluation Of Deferred Taxes	0.00%	[1]	(3.10%)	[1]	1.30%	[1]	(3.70%)	[1]
Other	(2.00%)	[1]	(1.80%)	[1]	(1.90%)	[1]	2.80%	[1]
Total provision for income taxes (combined with increase in income tax benefit payable to former stockholder	30.80%	[1],[2]	28.10%	[1],[2]	25.00%	[1],[2]	32.70%	[1],[2]
Portion Relating Payable To Former Stockholder [Member]
U.S. state taxes, net of Federal benefit	0.00%	[1]	(0.30%)	[1]	5.30%	[1]	(0.70%)	[1]
Effective Income Tax Rate Reconciliation, Deductions, Other	1.80%	[1]	1.80%	[1]	4.40%	[1]	1.50%	[1]
Effective Income Tax Rate Reconciliation, Revaluation Of Deferred Taxes	0.00%	[1]	(25.60%)	[1]	0.00%	[1]	(20.20%)	[1]
Other	(1.40%)	[1]	(1.80%)	[1]	(1.30%)	[1]	(5.50%)	[1]
Total increase in income tax benefit payable to former stockholder	0.40%	[1],[2]	(25.90%)	[1],[2]	8.40%	[1],[2]	(24.90%)	[1],[2]

[1] As a result of a partial increase in the tax basis of our tangible and intangible assets attributable to transactions entered into by affiliates controlled by a former significant stockholder at the time of the Company's 2004 initial public offering, the Company may pay reduced tax amounts to the extent it generates sufficient taxable income in the future. The Company is obligated to remit to an affiliate of the former stockholder 85% of any cash savings in U.S. Federal income tax, California franchise tax and certain other related tax benefits. Refer to the Company's 2010 Form 10-K for a more detailed description.

[2] For the six months ended June 30, 2011, includes an aggregate benefit of $4.3 million related to the Company's determination, during the first quarter of 2011, of its ability to claim certain tax deductions related to prior years. For the six months ended June 30, 2010, includes an adjustment primarily related to deferred tax assets (net of valuation allowance) of approximately $2.1 million associated with prior year taxes.