Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net unrecognized tax benefit	$ 53,300,000		$ 53,300,000		$ 43,900,000
Income tax interest and penalties accrued	0		0
Deferred tax assets	$ 134,100,000		$ 134,100,000
Effective tax rate	16.60%	(7.60%)	8.10%	5.80%
U.S. federal statutory rate			35.00%