Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions		3 Months Ended	12 Months Ended
	Jul. 29, 2015	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Class of Stock [Line Items]
Cost of shares repurchased		$ 1,187,000,000	$ 3,622,000,000
Common Class A
Class of Stock [Line Items]
Stock repurchase expiration date	Dec. 31, 2018			Dec. 31, 2016
Stock repurchase value	$ 13,700,000,000			$ 7,700,000,000
Increase in share repurchase value	$ 6,000,000,000
Number of shares repurchased		28.9
Average cost of shares repurchased		$ 41.04
Cost of shares repurchased		$ 1,200,000,000
Stock repurchase remaining amount		$ 4,300,000,000