Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Purchase of common stock	$ (564)	$ (1,463)
Withholding taxes paid for conversion of employee stock awards	1,319	1,436
OPERATING ACTIVITIES:
Net earnings from continuing operations	15,682	9,796
Net earnings from discontinued operations	196	192
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	46,320	39,033
Pension and post-retirement	942	1,995
Deferred income taxes	5,053	6,149
Amortization of stock-based compensation	1,014	784
Net (gain) loss on financial instruments	(2,343)	(209)
Changes in assets and liabilities:
Accounts receivable	10,567	(6,487)
Inventory and prepaid supplies	4,871	(4,413)
Accounts payable	(608)	6,932
Unearned revenue	(3,752)	4,765
Accrued expenses, salaries, wages, benefits and other liabilities	(10,079)	(9,911)
Pension and post-retirement assets	(4,584)	(3,039)
Other	2,335	283
NET CASH PROVIDED BY OPERATING ACTIVITIES	68,842	44,210
INVESTING ACTIVITIES:
Capital expenditures	(79,092)	(83,786)
Proceeds from property and equipment	16,763	0
Investment in nonconsolidated affiliate	(2,450)	(640)
Redemption of long term deposits	0	4,725
NET CASH (USED IN) INVESTING ACTIVITIES	(64,779)	(79,701)
FINANCING ACTIVITIES:
Principal payments on long term obligations	(17,390)	(10,337)
Proceeds from borrowings	30,000	60,000
Payments for financing costs	(17)	0
NET CASH PROVIDED BY FINANCING ACTIVITIES	10,710	46,764
NET INCREASE IN CASH AND CASH EQUIVALENTS	14,773	11,273
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	32,699	16,358
CASH AND CASH EQUIVALENTS AT END OF PERIOD	47,472	27,631
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid, net of amount capitalized	2,413	3,406
Federal alternative minimum and state income taxes paid	526	113
SUPPLEMENTAL NON-CASH INFORMATION:
Accrued capital expenditures	24,629	18,251
Net (gain) loss on financial instruments	$ (885)	$ 1,869