Operating Leases - Lessee (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
Ground Lease Expiration Date	2101
Office Lease Expiration Date	2027
Deferred Compensation Liability, Current and Noncurrent	$ 28,632,000	$ 27,621,000
Operating leases expenses	9,500,000	$ 8,900,000	$ 8,500,000
Operating Leases, Future Minimum Payments Due [Abstract]
2015	8,450
2016	7,599
2017	7,374
2018	7,106
2019	6,393
Thereafter	253,900
Total	$ 290,822