Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Net income (loss)	$ 531,421	[1]	$ (16,417)	[1]	$ (11,724)
Other comprehensive income, net of tax:
Unrealized gain on interest rate swaps	6,419		6,402		247
Comprehensive income (loss)	$ 537,840		$ (10,015)		$ (11,477)

[1] Some amounts do not add across due to rounding differences in quarterly amounts and due to the impact of differences between the quarterly and annual weighted average share calculations.