Equity and Accumulated Other Comprehensive Loss, Net (Noncontrolling Interests in Operating Partnership) (Details) $ in Millions	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares
Class of Stock [Line Items]
Partners' capital account units (in units)	205,470,300	159,019,118
Percentage of total	96.00%	98.50%
Common stock conversion ratio	1
Redeemable Noncontrolling Interest, Equity, Common, Redemption Value | $	$ 887.0	$ 226.3
Common units held by third parties
Class of Stock [Line Items]
Common units held by third parties (in units)	6,899,094	1,141,814
Percentage of total	3.20%	0.70%
Incentive units held by employees and directors (see note 14)
Class of Stock [Line Items]
Incentive units held by employees and directors (in units)	1,590,001	1,333,849
Percentage of total	0.80%	0.80%
Noncontrolling Interests in Operating Partnership
Class of Stock [Line Items]
Partners' capital account units (in units)	213,959,395	161,494,781
Percentage of total	100.00%	100.00%