CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 1,752	[1],[2]	$ 36,102	$ 39,022	$ 40,758	$ 44,246	$ 23,659	$ 30,547	$ 50,974	$ 117,634	$ 149,426	$ 194,332
Other comprehensive income (loss) net of tax effect:
Derivatives										(30,228)	6,965	36,072
Foreign currency translation										(667)
Comprehensive income										$ 86,739	$ 156,391	$ 230,404

[1] Includes franchise tax settlement of $12,590 before income tax effect ($8,058, net of income tax effect).

[2] Includes loss on early extinguishment of debt of $27,279 before income tax effect ($17,459 net of income tax effect).