Annual report pursuant to Section 13 and 15(d)

Business and Summary of Significant Accounting Principles (Asset Retirement Obligation) (Details)

v2.4.0.6
Business and Summary of Significant Accounting Principles (Asset Retirement Obligation) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Balance, beginning $ 15,223 $ 14,035  
Liabilities Incurred 660 613 1,253
Accretion Expense (508) (619) (289)
Liability Settled (111) (44)  
Balance, ending $ 16,280 $ 15,223 $ 14,035