Guarantor Condensed Consolidating Statements of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income	$ 41,391	$ 58,722
Other comprehensive income	(11,515)	(6,614)
Total comprehensive income attributable to common stockholders	29,876	52,108
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	41,102	57,620
Other comprehensive income	(11,226)	(5,512)
Total comprehensive income attributable to common stockholders	29,876	52,108
Subsidiary Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	12,452
Other comprehensive income	0
Total comprehensive income attributable to common stockholders	12,452
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	19,424
Other comprehensive income	0
Total comprehensive income attributable to common stockholders	19,424
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	55,108	78,522
Other comprehensive income	(11,226)	(5,512)
Total comprehensive income attributable to common stockholders	43,882	73,010
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(86,695)	(77,420)
Other comprehensive income	10,937	4,410
Total comprehensive income attributable to common stockholders	$ (75,758)	$ (73,010)