Debt - Selected Information about Debt Issues (Detail) - USD ($)	Dec. 31, 2021	Jul. 15, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt, par value, gross	$ 1,715,612,000
Current maturity of long-term debt, par value	150,000,000
Par Value	1,565,612,000
Total short-term debt, par value	480,033,000
Total debt, par value	2,045,645,000
Unamortized discount & issuance costs, noncurrent	(19,366,000)
Unamortized discount & issuance costs, current maturities	(248,000)
Unamortized discount & issuance costs, long-term debt	(19,118,000)
Unamortized discount & issuance costs, current	(389,000)
Total debt, unamortized discount & issuance costs,	(19,507,000)
Debt	2,026,138,000		$ 1,922,804,000
Long-term debt, net, book value	1,696,246,000		1,667,886,000
Current maturity of long-term debt, book value	149,752,000		0
Long-term debt	1,546,494,000		1,667,886,000
Total short-term debt, book value	479,644,000		254,918,000
Total debt, book value	2,026,138,000		1,922,804,000
Long-term debt, gross, fair value	1,820,293,000
Current maturity of term loan, fair value	153,284,000
Long-term debt, net, fair value	1,667,009,000
Total short-term debt, fair value	483,176,000
Total debt, fair value	2,150,185,000
Commercial Paper
Debt Instrument [Line Items]
Total short-term debt, par value	330,033,000
Unamortized discount & issuance costs, current	(141,000)
Total short-term debt, book value	329,892,000		254,918,000
Total short-term debt, fair value	$ 329,892,000
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	(396,000)
Debt	165,216,000		164,954,000
Long-term debt, gross, fair value	$ 180,444,000
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	(248,000)
Debt	149,752,000		149,414,000
Long-term debt, gross, fair value	153,284,000
Senior Notes Due 2022 | Consolidation eliminations | Subsidiaries
Debt Instrument [Line Items]
Par Value	150,000,000
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	(5,051,000)
Debt	544,949,000		544,328,000
Long-term debt, gross, fair value	$ 625,801,000
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	(4,222,000)
Debt	395,778,000		395,157,000
Long-term debt, gross, fair value	$ 395,208,000
Junior Subordinated Debentures Due 2056
Debt Instrument [Line Items]
Coupon Rate	4.25%
Par Value		$ 300,000,000
Debt			290,652,000
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	(1,604,000)
Debt	123,396,000		123,381,000
Long-term debt, gross, fair value	$ 128,856,000
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	(7,845,000)
Debt	317,155,000		$ 0
Long-term debt, gross, fair value	$ 336,700,000