Debt Obligations - Additional Information on Repurchase of Outstanding Unsecured Notes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Extinguishment Of Debt [Line Items]
Principal	$ 0	$ 376,174,000	$ 29,250,000
Repurchase Amount	0	383,768,000	31,369,000
Gain (Loss) on Early Extinguishment of Debt	$ 0	(7,594,000)	(2,119,000)
Acceleration of Deferred Financing		152,000	40,000
$250.0M 5.400% Guaranteed Notes due 2014 [Member]
Extinguishment Of Debt [Line Items]
Principal		218,549,000	19,830,000
Repurchase Amount		219,404,000	20,853,000
Gain (Loss) on Early Extinguishment of Debt		(855,000)	(1,020,000)
Acceleration of Deferred Financing		9,000	16,000
7.50% Guaranteed Notes due May 15, 2015 [Member]
Extinguishment Of Debt [Line Items]
Principal		157,625,000	8,910,000
Repurchase Amount		164,364,000	9,945,000
Gain (Loss) on Early Extinguishment of Debt		(6,739,000)	(1,036,000)
Acceleration of Deferred Financing		$ 143,000	23,000
$250.0M 6.00% Guaranteed Notes due 2016 [Member]
Extinguishment Of Debt [Line Items]
Principal			510,000
Repurchase Amount			571,000
Gain (Loss) on Early Extinguishment of Debt			(63,000)
Acceleration of Deferred Financing			$ 1,000