Stock-Based Compensation Plans (Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Shares
Closing Balance (in shares)	10,495,039
Options outstanding - end of the year (in shares)	6,690,250
Per share weighted average exercise prices
Closing Balance (in dollars per shares)	$ 21.67
Options exercisable - end of the year (in dollars per share)	$ 25.57
Stock Options
Shares
Closing Balance (in shares)	9,122,762	8,771,600
Granted (in shares)	2,553,510	1,758,760
Canceled (in shares)	(63,517)	(157,176)
Expired (in shares)	(1,117,716)	(1,250,422)
Closing Balance (in shares)	10,495,039	9,122,762
Options outstanding - end of the year (in shares)	6,690,250	7,140,772
Per share weighted average exercise prices
Opening Balance (in dollars per shares)	$ 27.13	$ 31.26
Granted (in dollars per share)	13.16	16.87
Canceled (in dollars per share)	20.34	19.48
Expired (in dollars per share)	46.88	42.62
Closing Balance (in dollars per shares)	21.67	27.13
Options exercisable - end of the year (in dollars per share)	$ 25.57	$ 27.47