Income Taxes - Summary of Tax Credit Carryforwards (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Taxes Disclosure [Line Items]
Net operating loss carryover	$ 476.2	$ 454.0
Tax credit carryover	72.9	79.7
Capital loss carryover	7.8	$ 8.6
Net operating loss carryover valuation allowance	407.0
Tax credit carryover valuation allowance	40.0
Capital loss carryover valuation allowance	7.8
1-5 Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	27.9
Tax credit carryover	17.1
Capital loss carryover	1.3
6-10 Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	40.8
Tax credit carryover	53.1
11+ Years [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	282.1
Tax credit carryover	1.6
Indefinite [Member]
Income Taxes Disclosure [Line Items]
Net operating loss carryover	125.4
Tax credit carryover	1.1
Capital loss carryover	$ 6.5