Goodwill and Other Intangibles (Narratives) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Finite-Lived Intangible Assets, Net
Goodwill, acquired	$ 348,972,000
Amortization of intangible assets	39,900,000	21,000,000
Real Estate Investments
Finite-Lived Intangible Assets, Net
Goodwill, acquired	$ 348,972,000
Maximum
Finite-Lived Intangible Assets, Net
Finite lived intangible assets useful life	40 years
Maximum | Below-market ground lease
Finite-Lived Intangible Assets, Net
Finite lived intangible assets useful life	134 years
Minimum
Finite-Lived Intangible Assets, Net
Finite lived intangible assets useful life	1 year