Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating ground leases [Abstract]
Rental property expense	$ 2,800,000	$ 1,500,000	$ 1,400,000
Operating ground leases, scheduled future minimum payments [Abstract]
Operating leases, future minimum payments due, 2014	3,044,000
Operating leases, future minimum payments, 2015	3,076,000
Operating leases, future minimum payments, 2016	3,109,000
Operating leases, future minimum payments, 2017	3,143,000
Operating leases, future minimum payments, 2018	3,179,000
Operating leases, future minimum payments, thereafter	116,139,000
Operating leases, total future minimum payments due	131,690,000
Lease and Contractual Commitments [Abstract]
Lease and contractual commitments	233,800,000
Accrued amount of lease and contractual commitments	25,900,000
DLF I obligation [Abstract]
Excess contribution, gross	7,200,000
Term to repay excess contribution (in years)	14 years
Excess contribution, initial repayment date	3/12/1999
Excess contribution, net discounted amount	3,800,000
Excess contribution, discount rate	9.62%
Excess contribution, payments	200,000	600,000	600,000
Excess contribution, discounted balance		$ 200,000