Disclosure Of Fair Value Of Financial Instruments (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Disclosure Of Fair Value Of Financial Instruments [Abstract]    
Fair value of Company's long-term debt $ 2,125,451,000 $ 2,133,214,000
Book value of Company's long-term debt $ 2,107,572,000 $ 2,088,654,000