Commitments and contingencies (Tables)

6 Months Ended

Jun. 30, 2020

Commitments and Contingencies Disclosure [Abstract]

Schedule of lease balances within the consolidated balance sheets

The following table presents the lease balances within the Consolidated Balance Sheets as of June 30, 2020 and December 31, 2019:

(millions)	Balance Sheet Classification	June 30, 2020		December 31, 2019
Operating lease right-of-use assets	Other assets		$28.8		$27.4
Current lease liabilities	Other liabilities		$9.1		$8.3
Non-current lease liabilities	Other liabilities		$21.4		$21.0

Schedule of weighted average remaining lease term and weighted average discount rate

The following table presents weighted average remaining lease term and weighted average discount rate as of June 30, 2020:

Weighted average lease term (years) as at June 30, 2020
Leased offices	7 years
Leased equipment	3 years
Weighted average discount rate:
Leased offices	3.3	%
Leased equipment	3.4	%

Schedule of future annual minimum rental payments required under non cancellable leases for office space

The following table presents future annual minimum rental payments required under non-cancellable leases and the present value discount to arrive at total lease liability as of June 30, 2020:

(Millions)	Future Payments
2020	$	4.5
2021	9.6
2022	9.4
2023	5.6
2024	2.3
2025 and after	1.1
Total future annual minimum rental payments as of June 30, 2020	32.5
Less: present value discount	(2.0		)
Total lease liability as of June 30, 2020	$	30.5