Debt (Details) (USD $) In Thousands, unless otherwise specified																									6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series A, due 2016, 4.05 Percent [Member]	Dec. 31, 2012 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series A, due 2016, 4.05 Percent [Member]	Jun. 30, 2013 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series A, due 2016, 5.00 Percent [Member]	Dec. 31, 2012 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series A, due 2016, 5.00 Percent [Member]	Jun. 30, 2013 Senior Notes, Series A, due 2019, 10.17 percent [Member]	Dec. 31, 2012 Senior Notes, Series A, due 2019, 10.17 percent [Member]	Jun. 30, 2013 Senior Notes, Series B, due 2019, 9.6 percent [Member]	Dec. 31, 2012 Senior Notes, Series B, due 2019, 9.6 percent [Member]	Jun. 30, 2013 Pennvest Loan, due 2019, 1.00 percent [Member]	Dec. 31, 2012 Pennvest Loan, due 2019, 1.00 percent [Member]	Jun. 30, 2013 Senior Notes, Series C, due 2020, 10.05 percent [Member]	Dec. 31, 2012 Senior Notes, Series C, due 2020, 10.05 percent [Member]	Jun. 30, 2013 Senior Notes, Series D, due 2022, 8.43 percent [Member]	Dec. 31, 2012 Senior Notes, Series D, due 2022, 8.43 percent [Member]	Jun. 30, 2013 Variable Rate Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds Series 2008A due 2029 [Member]	Dec. 31, 2012 Variable Rate Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds Series 2008A due 2029 [Member]	Jun. 30, 2013 Industrial Development Authority Revenue Bonds, series 2006, due 2036, 4.75 percent [Member]	Dec. 31, 2012 Industrial Development Authority Revenue Bonds, series 2006, due 2036, 4.75 percent [Member]	Jun. 30, 2013 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series 2008B, due 2038, 6.00 percent [Member]	Dec. 31, 2012 Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds, Series 2008B, due 2038, 6.00 percent [Member]	Jun. 30, 2013 Monthly Senior Notes, Series 2010A, due 2040, 5.00 percent [Member]	Dec. 31, 2012 Monthly Senior Notes, Series 2010A, due 2040, 5.00 percent [Member]	Jun. 30, 2013 Renewed Line of Credit, First Note [Member]	Jun. 30, 2013 Renewed Line of Credit, Second Note [Member]	Jun. 30, 2013 Renewed Line of Credit, Third Note [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 84,957	$ 84,975	$ 2,350	$ 2,350	$ 4,950	$ 4,950	$ 6,000	$ 6,000	$ 5,000	$ 5,000	$ 272	$ 290	$ 6,500	$ 6,500	$ 7,500	$ 7,500	$ 12,000	$ 12,000	$ 10,500	$ 10,500	$ 14,885	$ 14,885	$ 15,000	$ 15,000
Less current maturities	(42)	(42)
Long-term portion	84,915	84,933
Renewed line of credit																									13,000	11,000	5,000
Revised maturity date																									May 01, 2015	May 01, 2015	Jun. 01, 2014
Demand deposit requirement, minimum	$ 0	$ 500