Summary of Significant Accounting Policies and New Accounting Pronouncements Summary o Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Millions	Jan. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss		$ (618)	$ (407)	$ (1)
Accounting Standards Update 2016-01 [Member] | Adjustments for New Accounting Principle, Early Adoption [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss	$ 174