Class of Stock [Domain] Class of Stock [Domain] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Class of Stock [Axis] Class of Stock [Axis] Security Exchange Name Security Exchange Name Entity Address, City or Town Entity Address, City or Town Soliciting Material Soliciting Material Cover [Abstract] Cover [Abstract] City Area Code City Area Code Common Stock, par value $5 per share Common Stock [Member] Amendment Flag Amendment Flag Entity Tax Identification Number Entity Tax Identification Number Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Pre-commencement Tender Offer Pre-commencement Tender Offer Entity Emerging Growth Company Entity Emerging Growth Company Series 2025A 6.50% Junior Subordinated Notes due 2085 Series 2025A 6.50% Junior Subordinated Notes due 2085 [Member] Series 2025A 6.50% Junior Subordinated Notes due 2085 Series 2020A 4.95% Junior Subordinated Notes Due 2080 [Member] Series 2020A 4.95% Junior Subordinated Notes Due 2080 [Member] Series 2020A 4.95% Junior Subordinated Notes Due 2080 [Member] Series 2020C 4.20% Junior Subordinated Notes due 2060 Series 2020C 4.20% Junior Subordinated Notes due 2060 [Member] Series 2020C 4.20% Junior Subordinated Notes due 2060 Entity Central Index Key Entity Central Index Key Entity File Number Entity File Number Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081 Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081 [Member] Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081 Entity Address, State or Province Entity Address, State or Province Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Address, Address Line One Entity Address, Address Line One Document Information [Line Items] Document Information [Line Items] Document Information [Table] Document Information [Table] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Written Communications Written Communications Series 2017B 5.25% Junior Subordinated Notes due 2077 Series 2017B 5.25% Junior Subordinated Notes Due 2077 [Member] Series 2017B 5.25% Junior Subordinated Notes Due 2077 [Member] Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Document Period End Date Document Period End Date Document Type Document Type