Stock-Based Compensation - Compensation Expense (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ (269)	$ 22,306	$ 13,584
Class B and E Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	0	19,860	12,320
Incentive Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ (269)	$ 2,446	$ 1,264