Fair Value Measurements - (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Fair value of assets and liabilities measured on a recurring basis

	AFS Investments			Interest Rate Swaps			Total
Fair value at December 31, 2012	$	59,145		$	(7,968	)	$	51,177
Investment accretion	3,451			—			3,451
Unrealized losses included in interest expense	—			(48		)	(48		)
Losses on interest rate swaps reclassified into interest expense from accumulated other comprehensive loss	—			1,678			1,678
Unrealized gains (losses) included in equity and partners’ capital	(4,188		)	1,734			(2,454		)
Fair value at December 31, 2013	$	58,408		$	(4,604	)	$	53,804
Investment accretion	3,827			—			3,827
Unrealized losses included in interest expense	—			(48		)	(48		)
Losses on interest rate swaps reclassified into interest expense from accumulated other comprehensive loss	—			1,685			1,685
Unrealized (losses) gains included in equity and partners’ capital	(1,192		)	(2,306		)	(3,498		)
Fair value at December 31, 2014	$	61,043		$	(5,273	)	$	55,770