Business Combinations (Unaudited Pro forma Information) (Details) - Parent Company [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 01, 2013
Business Acquisition [Line Items]
Purchase price for Colonial merger	$ 0	$ 0	$ 2,162,876
Colonial
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Assets Acquired			4,066,065
Business Acquisition, Purchase Price Allocation, Liabilities Assumed			(1,903,189)
Purchase price for Colonial merger			2,162,876	$ 2,162,876
Land | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			469,396
Building and Building Improvements | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			3,080,858
Furniture Fixtures And Equipment | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			96,377
Construction in Progress | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			113,368
Unimproved Land | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			58,400
Assets Held-for-sale | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			33,300
Finite-Lived Intangible Assets, Major Class Name | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			57,946
Cash and Cash Equivalents [Member] | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			63,454
Restricted Cash | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			6,825
Other Assets | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Assets Acquired			86,141
Debt | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Liabilities Assumed			(1,759,550)
Interest Rate Cash Flow Hedge Liability at Fair Value | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Liabilities Assumed			(14,961)
Other Liabilities | Colonial
Business Acquisition [Line Items]
Business Acquisition, PPA, Liabilities Assumed			$ (128,678)