Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commitments and contingencies
Structural or other improvement and repair costs incurred	$ 1,983	$ 841	$ 2,078	$ 942
Expected recovery through applicable indemnity of cost incurred expressed as percentage of total cost	80.00%		80.00%
Minimum
Commitments and contingencies
Estimated total structural and other improvement and repair costs related to lease contracts acquired in the Central Merger			$ 5,000
Maximum
Commitments and contingencies
Estimated total structural and other improvement and repair costs related to lease contracts acquired in the Central Merger			$ 20,000