Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Apr. 16, 2013
Loss Contingencies [Line Items]
IRS proposed adjustments to tax years 2000 through 2002, before penalty and interest			$ 16,500
Potential penalty, percentage of tax assessment			20.00%
Maximum term for option to appeal					90 days
Income taxes	23,218	3,783	27,417	7,584
Expected cash payment of tax, interest and penalties					13,000
2013 U.S Court Decision [Member]
Loss Contingencies [Line Items]
Income taxes	$ 16,569