Employee Share-Based Incentive Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of performance shares outstanding and accrued expense for performance shares awarded under the WTM Incentive Plan

The following table presents the performance share activity for the three and nine months ended September 30, 2022 and 2021 for performance shares granted under the WTM Incentive Plan:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2022			2021			2022			2021
Millions, except share amounts	Target Performance Shares Outstanding	Accrued Expense		Target Performance Shares Outstanding	Accrued Expense		Target Performance Shares Outstanding	Accrued Expense		Target Performance Shares Outstanding	Accrued Expense
Beginning of period	39,449	$	41.2	41,252	$	45.7	40,828	$	42.2	42,458	$	56.3
Shares paid (1)	—	—		(219)	(.6)		(14,625)	(26.4)		(14,336)	(35.2)
New grants	—	—		—	—		13,225	—		13,475	—
Forfeitures and   cancellations (2)	—	(.1)		(205)	.2		21	(.2)		(769)	.4
Expense recognized	—	11.9		—	(6.5)		—	37.4		—	17.3
End of period	39,449	$	53.0	40,828	$	38.8	39,449	$	53.0	40,828	$	38.8

(1) Includes WTM performance share payments in 2022 for the 2019-2021 performance cycle, which were paid in March 2022 at 172% of target and WTM performance share payments in 2021 for the 2018-2020 performance cycle, which were paid in March 2021 at 200% of target. 

(2) Amounts include changes in assumed forfeitures, as required under GAAP.

Share-based Compensation, Performance Shares Award Outstanding Activity

The following table presents performance shares outstanding and accrued expense for performance shares awarded under the WTM Incentive Plan as of September 30, 2022 for each performance cycle:

	Nine Months Ended September 30, 2022
Millions, except share amounts	Target Performance Shares Outstanding	Accrued Expense
Performance cycle:
2020 – 2022	13,350	$	31.9
2021 – 2023	13,475	14.7
2022 – 2024	13,225	7.2
Sub-total	40,050	53.8
Assumed forfeitures	(601)	(.8)
September 30, 2022	39,449	$	53.0

Summary of restricted shares activity

Restricted shares are grants of a specified number of common shares that generally vest at the end of a 34-month service period. The following table presents the unrecognized compensation cost associated with the outstanding restricted share awards for the three and nine months ended September 30, 2022 and 2021:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2022			2021			2022			2021
Millions,  except share amounts	Restricted Shares	Unamortized Issue Date Fair Value		Restricted Shares	Unamortized Issue Date Fair Value		Restricted Shares	Unamortized Issue Date Fair Value		Restricted Shares	Unamortized Issue Date Fair Value
Non-vested,
Beginning of period	38,350	$	23.0	38,280	$	23.2	37,850	$	15.9	43,105	$	15.2
Issued	—	—		—	—		13,225	13.8		13,475	16.1
Vested	—	—		(219)	—		(12,725)	—		(17,936)	—
Forfeited	—	—		(211)	(.2)		—	—		(794)	(.8)
Expense recognized	—	(3.8)		—	(3.6)		—	(10.5)		—	(11.1)
End of period	38,350	$	19.2	37,850	$	19.4	38,350	$	19.2	37,850	$	19.4