Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Deferred:
Total deferred tax expense (benefit)	$ (8,522)	$ 39,525
Total income tax expense (benefit)	$ 109,820	$ 42,957
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Effective income tax rate	62.70%	30.30%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	0.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	10.40%
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Percent		12.30%