Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]
Income tax provision	$ 59,282,000	$ 34,713,000	$ 109,313,000	$ 69,168,000
Effective income tax rate, percent	37.30%	34.40%	36.60%	35.00%
Effective income tax rate, at federal statutory income tax rate, percent	35.00%	35.00%	35.00%	35.00%
Cash paid for taxes, net of refunds received			$ 58,100,000	$ 9,700,000