Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Environmental liabilities	$ 1,400		$ 1,400		$ 1,400
Liability For Potential Settlement Of Ongoing SEC Investigation	3,500		3,500
Accrued Professional Fees	3,900		3,900
Other Expense, Nonoperating, Cost Of Ongoing SEC Investigation	7,430	$ 0	7,430	$ 0
Guarantor Obligations [Line Items]
Purchase obligations, total	4,400		4,400
Purchase obligations, 2015	2,700		2,700
Purchase obligations, 2016	200		200
Purchase obligations, 2017	1,500		1,500
Tax Year 2022 To 2024
Guarantor Obligations [Line Items]
Deferred Tax Liabilities, Gross	61,800		61,800
Tax Year 2029
Guarantor Obligations [Line Items]
Deferred Tax Liabilities, Gross	69,300		69,300
Surety bonds | Certain development projects
Guarantor Obligations [Line Items]
Commitment obligations	$ 8,300		$ 8,300		$ 8,300