Employee Incentive Plans, Weighted Average Grant Date Fair Value (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	$ 96.40
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value		$ 77.35	$ 76.82
TSR-Based Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	127.41	97.88	93.02
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	$ 109.38	$ 86.97	$ 88.00