Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Senior Notes due 2022 Senior Notes due 2022 [Member] Senior Notes due 2022 Entity Address, City or Town Entity Address, City or Town Entities [Table] Entities [Table] Soliciting Material Soliciting Material Entity Address, Address Line One Entity Address, Address Line One Security Exchange Name Security Exchange Name City Area Code City Area Code Cover page. Entity Central Index Key Entity Central Index Key Entity Tax Identification Number Entity Tax Identification Number Entity File Number Entity File Number Document Type Document Type Entity Emerging Growth Company Entity Emerging Growth Company Title of 12(b) Security Title of 12(b) Security Amendment Flag Amendment Flag Entity Address, State or Province Entity Address, State or Province Trading Symbol Trading Symbol Document Period End Date Document Period End Date Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Written Communications Written Communications Pre-commencement Tender Offer Pre-commencement Tender Offer Class of Stock [Axis] Class of Stock [Axis] Floating Rate Notes due 2020 Floating Rate Notes due 2020 [Member] Floating Rate Notes due 2020 No Trading Symbol Flag No Trading Symbol Flag Common Stock, $.01 par value Common Stock, $.01 par value [Member] Common Stock, $.01 par value Local Phone Number Local Phone Number Floating Rate Notes due 2021 Floating Rate Notes due 2021 [Member] Floating Rate Notes due 2021 Entity Address, Postal Zip Code Entity Address, Postal Zip Code Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Class of Stock [Domain] Class of Stock [Domain]