CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities	$ 102,059	$ 89,669
Cash Flows from Investing Activities:
Capital Expenditures	(141,585)	(134,945)
Purchase of Available for Sale Securities	(6,059)	0
Net Proceeds from Sale of Restricted Investments in Margin Account	12,581	3,333
Investment in Long-Term Receivables	(3,381)	(3,410)
Proceeds from Long-Term Receivables	2,040	3,536
Notes Receivable	(9,887)	0
Purchase of Company Owned Life Insurance	(765)	(526)
Investment in Affiliate	(1,766)	0
Advances on Notes Receivable - Affiliate	(1,514)	(1,922)
Repayment of Notes Receivable - Affiliate	4,612	5,639
Net Cash Used in Investing Activities	(145,724)	(128,295)
Cash Flows from Financing Activities:
Net Borrowings from (Repayments of) Short-Term Credit Facilities	120,300	(147,200)
Proceeds from Issuance of Long-Term Debt	0	189,000
Principal Repayments of Long-Term Debt	(64,000)	0
Payments for Issuance of Long-Term Debt	0	(1,204)
Dividends on Common Stock	(17,192)	(15,510)
Proceeds from Sale of Common Stock	3,596	17,119
Net Cash Provided by Financing Activities	42,704	42,205
Net (Decrease) Increase in Cash and Cash Equivalents	(961)	3,579
Cash and Cash Equivalents at Beginning of Period	4,171	3,818
Cash and Cash Equivalents at End of Period	$ 3,210	$ 7,397