Consolidated Variable Interest Entity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)
Consolidated Variable Interest Entity [Abstract]
Rentable square feet of office property under development (in sq feet) | ft²	1,200,000
Assets and liabilities of consolidated variable interest entity [Abstract]
Development in-process	$ 184,400	$ 172,706
Accounts payable, accrued expenses and other liabilities	$ 264,986	$ 286,911
Consolidated Variable Interest Entity [Member]
Consolidated Variable Interest Entity [Abstract]
Rentable square feet of office property under development (in sq feet) | ft²	150,000
Total anticipated development costs	$ 71,300
Contribution of cash to acquire interest in consolidated joint venture	$ 20,000
Interest in consolidated joint venture (in hundredths)	80.00%
Partner's contribution of property to acquire interest in consolidated joint venture	$ 5,000
Advance to consolidated affiliate	46,300
Amount of loan funded to affiliate	2,200
Assets and liabilities of consolidated variable interest entity [Abstract]
Development in-process	29,073
Accounts payable, accrued expenses and other liabilities	$ 1,669
Consolidated Variable Interest Entity [Member] | London Interbank Offered Rate (LIBOR) [Member]
Consolidated Variable Interest Entity [Abstract]
Variable interest rate basis	LIBOR plus 250 basis points
Interest rate, basis spread (in hundredths)	2.50%
Variable Interest Entity [Member]
Consolidated Variable Interest Entity [Abstract]
Partner's interest in consolidated joint venture (in hundredths)	20.00%
Variable Interest Entity [Member] | Consolidated Variable Interest Entity [Member]
Consolidated Variable Interest Entity [Abstract]
Partner's interest in consolidated joint venture (in hundredths)	20.00%