Long-Term Debt - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Long-term debt, interest percentage	6.54%
Debt Instrument, Unused Borrowing Capacity, Amount	$ 255.0
Long-term debt including current maturities	1,300.0
Long-term Debt and Lease Obligation	1,287.2	$ 1,205.6
Total long-term debt, net of current maturities	1,261.7	1,187.1
Unamortized Debt Issuance Expense	(3.6)	(3.7)
Long-term Debt and Lease Obligation, Current	$ (25.5)	(18.5)
Uncollateralized Senior Note Due On Two Thousand Twenty Six [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	5.68%
Long-term debt including current maturities	$ 5.8	8.7
Uncollateralized Senior Note Due December Two Thousand Thirty Four [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	2.98%
Long-term debt including current maturities	$ 70.0	70.0
Uncollateralized Senior Note Due On May 2 Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	6.43%
Long-term debt including current maturities	$ 2.8	3.5
Uncollateralized Senior Note Two Due on December Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.73%
Long-term debt including current maturities	$ 8.0	10.0
Uncollateralized Senior Notes Due On Two Thousand Twenty Nine [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.88%
Long-term debt including current maturities	$ 25.0	30.0
Uncollateralized Senior Note Due April Two Thousand Thirty Two [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.25%
Long-term debt including current maturities	$ 52.5	59.5
Uncollateralized Senior Note Due May Two Thousand Thirty Eight [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.48%
Long-term debt including current maturities	$ 50.0	50.0
Uncollateralized Senior Note Due November Two Thousand Thirty Eight [Member]
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.58%
Long-term debt including current maturities	$ 50.0	50.0
Uncollateralized Senior Note Due November Two Thousand Thirty Nine
Debt Instrument [Line Items]
Long-term debt including current maturities	$ 100.0	100.0
Uncollateralized Senior Note Due July Two Thousand Thirty Five
Debt Instrument [Line Items]
Long-term debt, interest percentage	3.00%
Long-term debt including current maturities	$ 50.0	50.0
Uncollateralized Senior Note Due August Two Thousand Thirty Five
Debt Instrument [Line Items]
Long-term debt, interest percentage	2.96%
Long-term debt including current maturities	$ 40.0	40.0
Uncollateralized Senior Note Due January Two Thousand Thirty Seven
Debt Instrument [Line Items]
Long-term debt, interest percentage	2.49%
Long-term debt including current maturities	$ 50.0	50.0
Equipment Security Note
Debt Instrument [Line Items]
Long-term debt, interest percentage	2.46%
Long-term debt including current maturities	$ 6.7	7.6
Uncollateralized Senior Note Due March 15, 2042
Debt Instrument [Line Items]
Long-term debt, interest percentage	2.95%
Long-term debt including current maturities	$ 50.0	$ 50.0
Uncollateralized Senior Note Due March 14, 2038
Debt Instrument [Line Items]
Long-term debt, interest percentage	5.43%
Uncollateralized Senior Note Due March 14, 2038 | Prudential [Member]
Debt Instrument [Line Items]
Long-term debt including current maturities	$ 80.0
Uncollateralized Senior Note Due October 2029
Debt Instrument [Line Items]
Long-term debt, interest percentage	5.20%
Uncollateralized Senior Note Due October 2029 | Prudential [Member]
Debt Instrument [Line Items]
Long-term debt including current maturities	$ 100.0