Equity and Capital - Noncontrolling Interest of Limited Partners (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Limited Partners' Capital Account [Line Items]
Document Fiscal Year Focus	2017
General Partners' Capital Account, Units Outstanding	171,364,908	104,497,000
Limited Partners' Capital Account, Units Outstanding	350,000	154,000
Partners' Capital Account, Units	171,714,810	104,651,000
Parent Company, Ownership Percentage of Outstanding Common Partnership Units of Operating Partnership	99.80%	99.90%
Parent Company [Member]
Limited Partners' Capital Account [Line Items]
Partners' Capital Account, Contributions	$ 13,478	$ 8,760	$ 717
Parent Company [Member] | Noncontrolling Interest Exchangeable Operating Partnership Units [Member]
Limited Partners' Capital Account [Line Items]
Partners' Capital Account, Units, Contributed	195,732
Partners' Capital Account, Contributions	$ 13,100	$ 0	$ 0