Share-Based Compensation Plans - Performance Share Awards Narrative (Details) - Performance-based Awards - shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSA, vesting conditions period (in years)	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSA, actual shares issued, percent	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSA, actual shares issued, percent	200.00%
2010 Leadership Performance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	1.3
2009 Leadership Performance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)		1.6
2008 Leadership Performance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)			0.8
2006 Performance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)			0.2