Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Level 2 | Accounts payable and accrued expenses | Interest rate swaps
Fair value of financial assets and liabilities
Fair value of derivative liabilities	$ 214
Level 2 | Other assets, net | Interest rate swaps
Fair value of financial assets and liabilities
Fair value of derivative assets	4,300
Mortgages Payable
Fair value of financial assets and liabilities
Unamortized balance of non-cash net premiums	5,100		$ 5,900
Deferred financing costs	209	$ 209	236
Notes and bonds payable
Fair value of financial assets and liabilities
Deferred financing costs	36,200		34,100
Unamortized balance of original issuance premiums	11,100		14,300
Carrying value
Fair value of financial assets and liabilities
Notes receivable issued in connection with property sales			5,300
Mortgages payable assumed in connection with acquisitions	306,800		320,300
Notes and bonds payable	5,400,000		5,250,000
Estimated fair value
Fair value of financial assets and liabilities
Notes receivable issued in connection with property sales			5,300
Mortgages payable assumed in connection with acquisitions	314,400		334,200
Notes and bonds payable	$ 5,391,900		$ 5,475,300