Condensed Consolidating Guarantor Financial Statements Details IS Summary (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income	$ 19,410,000	$ 11,173,000	$ 13,339,000	$ 16,788,000	$ 26,941,000	$ 19,528,000	$ 16,015,000	$ 22,682,000	$ 60,710,000	$ 85,166,000	$ 83,846,000
Comprehensive income									22,578,000	56,649,000	79,025,000
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income									60,710,000	85,166,000	83,846,000
Comprehensive income									22,578,000	56,649,000	79,025,000
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									41,520,000	52,775,000	54,076,000
Comprehensive income									41,520,000	52,775,000	54,076,000
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									46,445,000	53,335,000	52,710,000
Comprehensive income									46,445,000	53,335,000	52,710,000
Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income									(87,965,000)	(106,110,000)	(106,786,000)
Comprehensive income									$ (87,965,000)	(106,110,000)	(106,786,000)
Adjustments for New Accounting Pronouncement [Member]
Condensed Financial Statements, Captions [Line Items]
Net income										0	0
Comprehensive income										0	0
Adjustments for New Accounting Pronouncement [Member] | Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income										106,110,000	106,786,000
Comprehensive income										106,110,000	106,786,000
Adjustments for New Accounting Pronouncement [Member] | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income										3,120,000	1,459,000
Comprehensive income										3,120,000	1,459,000
Adjustments for New Accounting Pronouncement [Member] | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income										(3,120,000)	(1,459,000)
Comprehensive income										(3,120,000)	(1,459,000)
Adjustments for New Accounting Pronouncement [Member] | Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income										(106,110,000)	(106,786,000)
Comprehensive income										(106,110,000)	(106,786,000)
Scenario, Previously Reported [Member]
Condensed Financial Statements, Captions [Line Items]
Net income										85,166,000	83,846,000
Comprehensive income										66,749,000	83,035,000
Scenario, Previously Reported [Member] | Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income										(20,944,000)	(22,940,000)
Comprehensive income										(20,944,000)	(22,940,000)
Scenario, Previously Reported [Member] | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income										49,655,000	52,617,000
Comprehensive income										49,655,000	52,617,000
Scenario, Previously Reported [Member] | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income										56,455,000	54,169,000
Comprehensive income										38,038,000	53,358,000
Scenario, Previously Reported [Member] | Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income										0	0
Comprehensive income										0	0
Scenario, Adjustment [Member]
Condensed Financial Statements, Captions [Line Items]
Comprehensive income										(10,100,000)	(4,010,000)
Scenario, Adjustment [Member] | Parent Company
Condensed Financial Statements, Captions [Line Items]
Comprehensive income										(28,517,000)	(4,821,000)
Scenario, Adjustment [Member] | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Comprehensive income										0	0
Scenario, Adjustment [Member] | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Comprehensive income										18,417,000	811,000
Scenario, Adjustment [Member] | Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Comprehensive income										$ 0	$ 0