Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Withholding taxes paid for conversion of employee stock awards	$ 1,839	$ 1,521
OPERATING ACTIVITIES:
Net earnings from continuing operations	22,826	101,087
Net earnings from discontinued operations	4,162	305
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	229,280	210,641
Pension and post-retirement	2,916	11,775
Deferred income taxes	17,728	14,036
Amortization of stock-based compensation	5,786	5,281
Net loss (gain) on financial instruments	7,700	12,100
Changes in assets and liabilities:
Accounts receivable	13,066	13,842
Inventory and prepaid supplies	(8,927)	14
Accounts payable	13,466	(2,410)
Unearned revenue and grants	49,605	2,830
Accrued expenses, salaries, wages, benefits and other liabilities	(8,623)	5,129
Pension and post-retirement assets	(20,920)	(10,419)
Other	(3,990)	3,135
NET CASH PROVIDED BY OPERATING ACTIVITIES	423,284	307,138
INVESTING ACTIVITIES:
Expenditures for property and equipment	(394,295)	(336,944)
Proceeds from property and equipment	9,210	11,087
Investment in nonconsolidated affiliate	(9,053)	(21,762)
NET CASH USED IN INVESTING ACTIVITIES	(394,138)	(347,619)
FINANCING ACTIVITIES:
Principal payments on long term obligations	(584,923)	(38,906)
Proceeds from borrowings	80,000	70,000
Proceeds from bond issuance	500,000	0
Payments for financing costs	(7,507)	(1,081)
NET CASH (USED IN) PROVIDED BY FINANCING ACTIVITIES	(14,269)	27,992
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	14,877	(12,489)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	46,201	59,322
CASH AND CASH EQUIVALENTS AT END OF YEAR	61,078	46,833
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid, net of amount capitalized	36,060	45,399
Federal and state income taxes paid	758	533
SUPPLEMENTAL NON-CASH INFORMATION:
Accrued expenditures for property and equipment	25,832	35,528
Net (gain) loss on financial instruments	(56,072)	60,566
Net Income (Loss) Attributable to Noncontrolling Interest	11,762	12,458
Asset Impairment Charges	39,075	0
Proceeds from (Payments for) Other Financing Activities	$ 0	$ (500)