Employee Incentive Plans Employee Incentive Plans, Weighted Average Grant Date Fair Value (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 86.11	$ 72.09	$ 66.42
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	75.29	69.83	67.42
EVA-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share		0.00	0.00
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted-Average Grant-Date Fair Value per Share	$ 93.02	$ 95.68	$ 83.18