Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Supplemental Disclosure of Cash Flow Information:
Interest paid	$ 19,186	$ 13,062
Income taxes paid	60	88
Supplemental Disclosure of Noncash Investing and Financing Activities:
Accrued capital expenditures	5,696	5,688
Dividend distributions declared, but not paid	44,489	38,784
Issuance of operating partnership units in connection with an acquisition	610	0
Note receivable retired in connection with an acquisition	$ 2,494	$ 0