Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Taxes [Line Items]
Excess tax benefits recognized	$ 18
Foreign earnings repatriated			$ 1,500
Tax charge resulting from repatriation of earnings of foreign subsidiaries		$ 210
CP Venezuela
Income Taxes [Line Items]
Income tax benefit, principally related to changes in Venezuela foreign currency regime		$ 210