Intangible assets, net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Intangible assets, net
Accumulated amortization	$ (26,045)	$ (26,045)	$ (10,334)
Intangible assets, net	160,231	160,231	175,587
Amortization expense	4,983	8,902
Covenant not to compete
Intangible assets, net
Intangible assets	3,533	3,533	3,533
Trade names
Intangible assets, net
Intangible assets	15,443	15,443	15,088
Proprietary know how
Intangible assets, net
Intangible assets	34,650	34,650	34,650
Lease contract rights
Intangible assets, net
Intangible assets	51,650	51,650	51,650
Amortization expense	2,633	5,824
Management contract rights
Intangible assets, net
Intangible assets	$ 81,000	$ 81,000	$ 81,000