Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rates	11.10%	15.30%	5.70%	14.90%
Prepaid tax asset, net of amortization	$ 142,800,000		$ 142,800,000		$ 109,400,000
Unrecognized tax benefits	$ 1,500,000		1,500,000		0
Interest and penalties accrued for any uncertain tax position					$ 0
Penalties for uncertain tax positions			200,000
Interest for uncertain tax positions			$ 100,000