CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities	$ 123,425	$ 62,290
Cash Flows from Investing Activities:
Capital Expenditures	(192,497)	(147,759)
Proceeds from Sale of Property, Plant and Equipment	6	29
Net (Purchase of) Proceeds from Sale of Restricted Investments in Margin Account	(5,802)	9,532
Purchase of Restricted Investments with Escrowed Loan Proceeds	(47)	0
Investment in Long-Term Receivables	(5,012)	(4,178)
Proceeds from Long-Term Receivables	5,376	5,217
Purchase of Company Owned Life Insurance	(5,072)	(4,547)
Investment in Affiliate	(2,973)	(35,899)
Advances on Notes Receivable - Affiliate	(11,849)	(66,755)
Repayment of Notes Receivable - Affiliate	94,946	11,523
Other	0	(6,388)
Net Cash Used in Investing Activities	(122,924)	(239,225)
Cash Flows from Financing Activities:
Net Borrowings from (Repayments of) Short-Term Credit Facilities	38,600	(6,000)
Proceeds from Issuance of Long-Term Debt	0	200,000
Principal Repayments of Long-Term Debt	(25,000)	(35,000)
Payments for Issuance of Long-Term Debt	(30)	(1,820)
Premium for Early Retirement of Debt	0	(700)
Dividends on Common Stock	(28,246)	(24,452)
Proceeds from Sale of Common Stock	13,931	41,543
Net Cash (Used in) Provided by Financing Activities	(745)	173,571
Net Decrease in Cash and Cash Equivalents	(244)	(3,364)
Cash and Cash Equivalents at Beginning of Period	4,638	7,538
Cash and Cash Equivalents at End of Period	$ 4,394	$ 4,174