Income Taxes - Summary of Tax Credit Carryforwards (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Income Taxes Disclosure [Line Items]
Net operating loss carryover	$ 452.4	$ 484.3
Tax credit carryover	100.5	81.8
Capital loss carryover	7.4	$ 8.1
Net operating loss carryover valuation allowance	392.7
Tax credit carryover valuation allowance	41.7
Capital loss carryover valuation allowance	7.4
1-5 Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	50.3
Tax credit carryover	22.7
Capital loss carryover	0.0
6-10 Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	30.6
Tax credit carryover	72.7
11+ Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	245.5
Tax credit carryover	4.0
Indefinite [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	126.0
Tax credit carryover	1.2
Capital loss carryover	$ 7.4