Intangible assets, net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Intangible assets, net
Accumulated amortization	$ (17,447)		$ (10,334)
Intangible assets, net	167,293		175,587
Amortization expense	3,919	78
Covenant not to compete
Intangible assets, net
Intangible assets	3,533		3,533
Trade names
Intangible assets, net
Intangible assets	14,556		15,088
Proprietary know how
Intangible assets, net
Intangible assets	34,650		34,650
Lease contract rights
Intangible assets, net
Intangible assets	5,001		51,650
Amortization expense	3,191	0
Management contract rights
Intangible assets, net
Intangible assets	$ 81,000		$ 81,000