Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating ground leases [Abstract]
Rental property expense	$ 2,900	$ 3,400	$ 3,400
Operating ground leases, scheduled future minimum payments [Abstract]
Operating leases, future minimum payments, 2017	2,027
Operating leases, future minimum payments, 2018	2,063
Operating leases, future minimum payments, 2019	2,100
Operating leases, future minimum payments, 2020	2,139
Operating leases, future minimum payments, 2021	2,162
Operating leases, future minimum payments, thereafter	90,447
Operating leases, total future minimum payments due	100,938
Lease and Contractual Commitments [Abstract]
Lease and contractual commitments	263,000
Accrued amount of lease and contractual commitments	73,600
Contingent Consideration [Abstract]
Asset acquisition, contingent consideration liability	$ 0	900	3,300
Asset Acquisition Contingent Consideration [Member]
Contingent Consideration [Abstract]
Acquisition purchase price		5,200	15,800
Asset acquisition, contingent consideration liability		$ 900	$ 3,300
Term of contingent consideration payable (in days)		30 days
Contingent consideration expected payment date		Jun. 30, 2019	Mar. 31, 2020