Entity Central Index Key Entity Central Index Key Entity Address, Address Line One Entity Address, Address Line One Trading Symbol Trading Symbol Entity File Number Entity File Number Soliciting Material Soliciting Material Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code $100,000,000 Zero Coupon Callable Accreting Notes due January 15, 2043 $100,000 Zero Coupon Callable Accreting Notes due January 15, 2043 [Member] $100,000 Zero Coupon Callable Accreting Notes due January 15, 2043 Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Entities [Table] Entities [Table] Title of 12(b) Security Title of 12(b) Security Amendment Flag Amendment Flag Entity Information [Line Items] Entity Information [Line Items] Current Fiscal Year End Date Current Fiscal Year End Date Security Exchange Name Security Exchange Name Entity Registrant Name Entity Registrant Name Document Period End Date Document Period End Date Debt Instrument [Axis] Debt Instrument [Axis] Entity Tax Identification Number Entity Tax Identification Number Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Address, City or Town Entity Address, City or Town Local Phone Number Local Phone Number Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Written Communications Written Communications Cover [Abstract] $50,000,000 Zero Coupon Callable Accreting Notes due January 29, 2043 $50,000,000 Zero Coupon Callable Accreting Notes due January 29, 2043 [Member] $50,000,000 Zero Coupon Callable Accreting Notes due January 29, 2043 Document Type Document Type Entity Emerging Growth Company Entity Emerging Growth Company Entity Address, State or Province Entity Address, State or Province Pre-commencement Tender Offer Pre-commencement Tender Offer