Stock-Based Compensation Plans - Summary of Information of Stock Options Exercised (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common Stock [Abstract]
Aggregate value	[1]	$ 0	$ 3	$ 4
Cash received for exercise price		$ 0	$ 7	$ 19

[1] Includes stock options issued to retirement eligible employees.