Stock-Based Compensation Plans - Summary of Nonvested Restrict Stock Unit Activity (Details) - Restricted Stock [Member] - $ / shares		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning Balance	[1]	3,758,218
Granted		2,132,856
Vested		(1,597,255)
Forfeited		(76,232)
Undistributed vested awards	[2]	(654,333)
Ending Balance	[1]	3,563,254	3,758,218
Nonvested, Weighted Average Exercise Price (in usd per share)	[1]	$ 31.27
Granted, Weighted Average Grant Date Fair Value (in usd per share)		36.55	$ 28.71	$ 31.06
Vested, Weighted Average Exercise Price (in usd per share)		32.88
Forfeited, Weighted Average Exercise Price (in usd per share)		33.06
Undistributed Vested Awards, Weighted Average Grant Date Fair Value (in usd per share)	[2]	35.35
Nonvested, Weighted Average Exercise Price (in usd per share)	[1]	$ 32.92	$ 31.27
Fully Vested Stock Based Compensation Issued To Retirement Eligible Employees		1,097,630	975,116

[1] Excludes 1,097,630 and 975,116 of restricted stock units issued to retirement-eligible employees as of December 31, 2015 and 2014, respectively, as they are fully vested.

[2] Represents restricted stock units that vested but were not distributed to retirement-eligible employees during 2015.