Goodwill and Other Intangibles Intangible Lease Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Below-market leases, accumulated amortization	$ 19,123	$ 715
Below-market leases, weighted average remaining life	13 years 9 months
Below-market lease liabilities, net	317,838	77,169
Leases, Acquired-in-Place [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	236,096	60,753
Intangible lease assets, weighted average remaining life	12 years 8 months
Intangible lease assets, net	1,816,508	689,109
Leasing Commissions [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	505	155
Intangible lease assets, weighted average remaining life	6 years 8 months 12 days
Intangible lease assets, net	4,205	227
Above Market Leases [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	22,471	658
Intangible lease assets, weighted average remaining life	15 years 3 months
Intangible lease assets, net	355,269	8,693
Lease Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	259,100
Intangible lease assets, net	$ 2,175,982	$ 698,029