Employee Share-Based Incentive Compensation Plans - Performance Shares (Details) - Performance Shares - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Target Performance Shares Outstanding
Beginning of period (in shares)	40,828	42,458	42,473
Shares paid or expired (in shares)	(14,625)	(14,336)	(14,070)
New grants (in shares)	13,225	13,475	14,055
Forfeitures and cancellations (in shares)	21	(769)	0
Expense recognized (in shares)	0	0	0
End of period (in shares)	39,449	40,828	42,458
Accrued Expense
Beginning of period	$ 42.2	$ 56.3	$ 43.7
Shares paid or expired	(26.4)	(35.2)	(27.7)
New grants	0.0	0.0	0.0
Forfeitures and cancellations	(0.4)	0.4	(0.4)
Expense recognized	52.1	20.7	40.7
End of period	$ 67.5	$ 42.2	$ 56.3
Range Of Performance Cycle From 2019 to 2021 | W T M Incentive and Phantom Plan
Accrued Expense
Payout for maximum growth target percentage	172.00%
Range Of Performance Cycle From 2018 to 2020 | W T M Incentive and Phantom Plan
Accrued Expense
Payout for minimum growth target percentage		200.00%
Range Of Performance Cycle From 2017 to 2019 | W T M Incentive and Phantom Plan
Accrued Expense
Payout for maximum growth target percentage			180.00%
Payout for minimum growth target percentage			174.00%