New Issued Accounting Pronouncements (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) center capital_lease administrative_office lease	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities	$ 51,240	$ 55,280
Net cash used in financing activities	$ (92,018)	(10,444)
Acquisition related costs		49	$ 1,400
Number of lessor leases | lease	5,800
Number of properties with ground lease agreements | center	18
Number of administrative office leases | administrative_office	3
Number of capital leases | capital_lease	1
Capital leases assets, number of units | center	2
Obligations under capital leases	$ 21,000		21,000
Capitalized internal costs		2,000	$ 7,200
Accounting Standards Update 2016-09, Statutory Tax Withholding Component [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities		(4,800)
Net cash used in financing activities		$ 4,800