Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income tax expense	$ 20,121	$ 22,440	$ 70,989	$ 65,388
Effective tax rate	36.00%	36.00%	37.00%	40.00%
Federal statutory rate	35.00%	35.00%	35.00%	35.00%
State income tax expense	1,147	1,272	4,210	6,562
Tax expense related to uncertain tax positions including accrued interest		839	1,544	2,908
Tax benefit (expense) from decrease (increase) in valuation allowance	570	2,674	2,370	2,182
Adjustment to paid-in capital for excess tax benefits from share-based compensation			7,259
Decrease in current deferred income tax assets due to utilization of NOLs			50,000
Second component of tax deductible goodwill	3,210		3,210
Capital distribution net related party			2,596
Alternative Minimum Tax Credit [Member]
Tax credit carryforward	2,300		2,300
Foreign [Member]
Tax credit carryforward	$ 17,000		$ 17,000
Foreign [Member] | Minimum [Member]
Foreign tax credit carryforwards, expiration year			2014
Foreign [Member] | Maximum [Member]
Foreign tax credit carryforwards, expiration year			2022