Debt - Selected Information about Debt Issues (Detail) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term debt, par value, gross	$ 1,965,612,000
Current maturity of long-term debt, par value	315,612,000
Par Value	1,650,000,000
Total short-term debt, par value	495,612,000
Total debt, par value	2,145,612,000
Unamortized discount & issuance costs, noncurrent	(23,188,000)
Unamortized discount & issuance costs, current maturities	(331,000)
Unamortized discount & issuance costs, long-term debt	(22,857,000)
Unamortized discount & issuance costs, current	(486,000)
Total debt, unamortized discount & issuance costs,	(23,343,000)
Long-term debt, net, book value	1,942,424,000	$ 1,696,246,000
Current maturity of long-term debt, book value	315,281,000	149,752,000
Long-term debt	1,627,143,000	1,546,494,000
Total short-term debt, book value	495,126,000	479,644,000
Total debt, book value	2,122,269,000	2,026,138,000
Long-term debt, gross, fair value	1,811,001,000
Current maturity of term loan, fair value	321,419,000
Long-term debt, net, fair value	1,489,582,000
Total short-term debt, fair value	501,264,000
Total debt, fair value	1,990,846,000
Commercial Paper
Debt Instrument [Line Items]
Total short-term debt, par value	180,000,000
Unamortized discount & issuance costs, current	(155,000)
Total short-term debt, book value	179,845,000	329,892,000
Total short-term debt, fair value	$ 179,845,000
Senior Notes Due 2023
Debt Instrument [Line Items]
Coupon Rate	7.875%
Long-term debt, par value, gross	$ 165,612,000
Unamortized discount & issuance costs, noncurrent	(257,000)
Debt	165,355,000	165,216,000
Long-term debt, gross, fair value	$ 171,168,000
Senior Notes Due 2022
Debt Instrument [Line Items]
Coupon Rate	3.80%
Long-term debt, par value, gross	$ 150,000,000
Unamortized discount & issuance costs, noncurrent	(74,000)
Debt	149,926,000	149,752,000
Long-term debt, gross, fair value	150,251,000
Senior Notes Due 2022 | Consolidation eliminations | Subsidiaries
Debt Instrument [Line Items]
Long-term debt, net, book value	$ 150,000,000
Senior Notes Due 2028
Debt Instrument [Line Items]
Coupon Rate	4.55%
Long-term debt, par value, gross	$ 550,000,000
Unamortized discount & issuance costs, noncurrent	(4,725,000)
Debt	545,275,000	544,949,000
Long-term debt, gross, fair value	$ 541,486,000
Senior Notes Due 2030
Debt Instrument [Line Items]
Coupon Rate	2.15%
Long-term debt, par value, gross	$ 400,000,000
Unamortized discount & issuance costs, noncurrent	(4,001,000)
Debt	395,999,000	395,778,000
Long-term debt, gross, fair value	$ 327,492,000
Senior Notes Due June 15 2032
Debt Instrument [Line Items]
Coupon Rate	4.80%
Long-term debt, par value, gross	$ 250,000,000
Unamortized discount & issuance costs, noncurrent	(4,726,000)
Debt	245,274,000	0
Long-term debt, gross, fair value	$ 246,459,000
Junior Subordinated Debentures Due 2057
Debt Instrument [Line Items]
Coupon Rate	5.275%
Long-term debt, par value, gross	$ 125,000,000
Unamortized discount & issuance costs, noncurrent	(1,597,000)
Debt	123,403,000	123,396,000
Long-term debt, gross, fair value	$ 125,325,000
Junior Subordinated Debentures Due 2061
Debt Instrument [Line Items]
Coupon Rate	4.25%
Long-term debt, par value, gross	$ 325,000,000
Unamortized discount & issuance costs, noncurrent	(7,808,000)
Debt	317,192,000	$ 317,155,000
Long-term debt, gross, fair value	$ 248,820,000