Intangibles (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Intangibles
Gross intangible lease assets	$ 978	$ 984
Intangible assets, accumulated depreciation and amortization	439	380
Gross intangible lease liabilities	154	156
Intangible liabilities, accumulated depreciation and amortization	$ 108	$ 100