Equity-Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Equity-based compensation
Equity-based compensation	$ 1,936	$ 1,046	$ 3,582	$ 1,780
Unrecognized Equity-Based Compensation as of June 30, 2012	18,798		18,798
Equity-Based Compensation [Member]
Equity-based compensation
Equity-based compensation	1,418	836	2,868	1,464
Unrecognized Equity-Based Compensation as of June 30, 2012	15,123		15,123
Non-Controlling Interest [Member]
Equity-based compensation
Equity-based compensation	518	210	714	316
Unrecognized Equity-Based Compensation as of June 30, 2012	3,675		3,675
Weighted Average Years Remaining of Equity-Based Compensation as of June 30, 2012	3 years 2 months 12 days		3 years 2 months 12 days
Stock Appreciation Rights [Member]
Equity-based compensation
Equity-based compensation	618	526	1,226	1,034
Unrecognized Equity-Based Compensation as of June 30, 2012	5,268		5,268
Weighted Average Years Remaining of Equity-Based Compensation as of June 30, 2012	2 years 7 months 6 days		2 years 7 months 6 days
Restricted Stock [Member]
Equity-based compensation
Equity-based compensation	713	42	1,396	77
Unrecognized Equity-Based Compensation as of June 30, 2012	9,624		9,624
Weighted Average Years Remaining of Equity-Based Compensation as of June 30, 2012	3 years 4 months 24 days		3 years 4 months 24 days
Deferred Stock Units [Member]
Equity-based compensation
Equity-based compensation	87	268	246	353
Unrecognized Equity-Based Compensation as of June 30, 2012	$ 231		$ 231
Weighted Average Years Remaining of Equity-Based Compensation as of June 30, 2012	8 months 12 days		8 months 12 days