Equity - Narratives (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Distributions Per Share
Distributions declared per share (usd per share)	$ 0.1625	$ 0.1625	$ 0.325	$ 0.3250
Distributions payable	$ 57,349		$ 57,349		$ 56,859
Aggregate distributions			$ 114,468	$ 112,531

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Publisher FASB
-Name Accounting Standards Codification
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