Commitments and Contingencies - Maturities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Leases with purchase options, annualized base rent receivables in next five years and thereafter
Leases with purchase option, annualized base rent receivables in 2017	$ 16,202
Leases with purchase option, annualized base rent receivables in 2018	20,028
Leases with purchase option, annualized base rent receivables in 2019	14,411
Leases with purchase option, annualized base rent receivables in 2020	13,869
Leases with purchase option, annualized base rent receivables thereafter	56,405
Total leases with purchase option, annualized base rent receivables	$ 120,915
Number of properties with purchase options, annualized base rent receivables
Number of properties with a purchase option, annualized base rent receivables in 2017 | item	9
Number of properties with a purchase option, annualized base rent receivables in 2018 | item	4
Number of properties with a purchase option, annualized base rent receivables in 2019 | item	2
Number of properties with a purchase option, annualized base rent receivables in 2020 | item	4
Number of properties with a purchase option, annualized base rent receivables thereafter | item	32
Total number of properties with a purchase option, annualized base rent receivables | item	51
Rental Expense
Rental expense attributable to continuing operations	$ 10,000	$ 10,000	$ 8,000
Maximum remaining term of ground leases excluding extension options	99 years
Future minimum lease obligations under non-cancelable ground and other operating leases
Future minimum lease obligations under non-cancelable ground and other operating leases, 2017	$ 7,294
Future minimum lease obligations under non-cancelable ground and other operating leases, 2018	7,303
Future minimum lease obligations under non-cancelable ground and other operating leases, 2019	7,448
Future minimum lease obligations under non-cancelable ground and other operating leases, 2020	7,018
Future minimum lease obligations under non-cancelable ground and other operating leases, 2021	6,688
Future minimum lease obligations under non-cancelable ground and other operating leases, Thereafter	376,304
Future minimum lease obligations under non-cancelable ground and other operating leases, Total	$ 412,055