Share Repurchase Program and Dividend - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions			1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 10, 2015	Jan. 27, 2015	Apr. 30, 2015	Jun. 30, 2015	Jun. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, new authorized amount		$ 2,000,000,000
Share repurchase program completion date		Dec. 31, 2016			Dec. 31, 2016
Cash dividends declared per common share		$ 0.10	$ 0.10	$ 0.10	$ 0.20
Dividends payable, record date		Feb. 09, 2015	May 04, 2015
Dividends payable, payable date		Feb. 23, 2015	May 18, 2015
Total cash payment for dividends				$ 70,000,000	$ 140,000,000
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased (in shares)	0.1			17.3	21.1
Aggregate stock repurchase price	$ 4,000,000			$ 753,000,000	$ 943,000,000
Average cost per share				$ 43.53	$ 44.60