Commitments and Contingencies (Details 3) - Incentive Arrangements (USD $)			12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2009 Master Economic Incentives Agreement Certain Employment Levels	Dec. 31, 2013 Texas Enterprise Fund Grant	Dec. 31, 2013 Texas Enterprise Fund Grant Certain Employment Levels	Dec. 31, 2012 Texas Enterprise Fund Grant Certain Employment Levels Incentives received	Dec. 31, 2007 Texas Enterprise Fund Grant Certain Employment Levels Incentives received	Dec. 31, 2013 Texas Enterprise Fund Grant Certain Employment Levels Additional incentives that may be received in future
Incentive Arrangements
Duration of exemption from most property taxes associated with the Corporate headquarters			14 years
Incentive for meeting certain new job levels in the State of Texas						$ 3,500,000.0	$ 5,000,000.0	$ 13,500,000.0
Interest rate, per year, on amounts subject to a clawback if we eliminate jobs for which we have drawn funds					3.40%
Amount received that was deferred and recorded as other non-current liabilities	$ 36,268,000	$ 27,070,000		$ 8,500,000.0