Entity Listings [Table] Entity Listings [Table] Soliciting Material Soliciting Material Written Communications Written Communications Entity Listings [Line Items] Entity Listings [Line Items] Local Phone Number Local Phone Number Class of Stock [Domain] Class of Stock [Domain] Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] Address Type [Domain] Address Type [Domain] Amendment Flag Amendment Flag Entity Emerging Growth Company Entity Emerging Growth Company Entity File Number Entity File Number Security Exchange Name Security Exchange Name NYSE Texas, Inc. NYSE CHICAGO, INC. [Member] Entity Address, State or Province Entity Address, State or Province Entity Address, Address Line One Entity Address, Address Line One Former Address Former Address [Member] City Area Code City Area Code Cover page. Cover [Abstract] Document Period End Date Document Period End Date Exchange [Domain] Exchange [Domain] Pre-commencement Tender Offer Pre-commencement Tender Offer Class of Stock [Axis] Class of Stock [Axis] Entity Central Index Key Entity Central Index Key Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Tax Identification Number Entity Tax Identification Number Entity Addresses, Address Type [Axis] Entity Addresses, Address Type [Axis] Entity Registrant Name Entity Registrant Name Trading Symbol Trading Symbol Common Stock, $1.00 par value per share Common Stock [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Title of 12(b) Security Title of 12(b) Security Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Address, City or Town Entity Address, City or Town New York Stock Exchange NEW YORK STOCK EXCHANGE, INC. [Member] Document Type Document Type 4.250% Junior Subordinated Debentures Subordinated Debt [Member]