Supplemental Guarantor Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 146,428	$ 165,057	$ 96,426
Cash flows from investing activities:
Payments for capital expenditures	(140,465)	(221,370)	(164,933)
Proceeds from sales of assets	110,008	33,299	28,269
Net cash used in investing activities	(30,457)	(188,071)	(136,664)
Cash flows from financing activities:
Purchases of treasury stock	(4,290)
Proceeds from long-term debt			500,000
Principal payments on long-term debt			(500,000)
Payment of debt issuance costs			(11,967)
Other	(1,002)	(2,586)	(5,058)
Net cash provided by (used in) financing activities	(5,292)	(2,586)	(17,025)
Effect of exchange rate changes on cash	961	(3,135)	3,654
Net increase (decrease) in cash and cash equivalents	111,640	(28,735)	(53,609)
Cash, cash equivalents, and restricted cash at beginning of period	163,748	192,483	246,092
Cash, cash equivalents, and restricted cash at end of period	275,388	163,748	192,483
Eliminations [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities		(3,283)
Cash flows from financing activities:
Dividends paid		3,283
Net cash provided by (used in) financing activities		3,283
Parent [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	18,408	23,866	26,221
Cash flows from financing activities:
Purchases of treasury stock	(4,290)
Changes in notes with affiliated companies, net	(13,259)	(21,734)	(21,163)
Other	(859)	(2,132)	(5,058)
Net cash provided by (used in) financing activities	(18,408)	(23,866)	(26,221)
Issuer [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(12,879)	(2,013)	3,369
Cash flows from investing activities:
Payments for capital expenditures	(6,173)	(2,055)	(1,041)
Net cash used in investing activities	(6,173)	(2,055)	(1,041)
Cash flows from financing activities:
Proceeds from long-term debt			500,000
Principal payments on long-term debt			(500,000)
Payment of debt issuance costs			(11,967)
Changes in notes with affiliated companies, net	127,661	(19,787)	8,727
Other	(143)	(454)
Net cash provided by (used in) financing activities	127,518	(20,241)	(3,240)
Net increase (decrease) in cash and cash equivalents	108,466	(24,309)	(912)
Cash, cash equivalents, and restricted cash at beginning of period	102,224	126,533	127,445
Cash, cash equivalents, and restricted cash at end of period	210,690	102,224	126,533
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	128,409	150,510	89,739
Cash flows from investing activities:
Payments for capital expenditures	(112,994)	(207,640)	(148,738)
Proceeds from sales of assets	110,008	20,003	23,485
Net cash used in investing activities	(2,986)	(187,637)	(125,253)
Cash flows from financing activities:
Changes in notes with affiliated companies, net	(128,452)	22,564	4,648
Net cash provided by (used in) financing activities	(128,452)	22,564	4,648
Net increase (decrease) in cash and cash equivalents	(3,029)	(14,563)	(30,866)
Cash, cash equivalents, and restricted cash at beginning of period	6,360	20,923	51,789
Cash, cash equivalents, and restricted cash at end of period	3,331	6,360	20,923
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	12,490	(4,023)	(22,903)
Cash flows from investing activities:
Payments for capital expenditures	(21,298)	(11,675)	(15,154)
Proceeds from sales of assets		13,296	4,784
Net cash used in investing activities	(21,298)	1,621	(10,370)
Cash flows from financing activities:
Changes in notes with affiliated companies, net	14,050	18,957	7,788
Dividends paid		(3,283)
Net cash provided by (used in) financing activities	14,050	15,674	7,788
Effect of exchange rate changes on cash	961	(3,135)	3,654
Net increase (decrease) in cash and cash equivalents	6,203	10,137	(21,831)
Cash, cash equivalents, and restricted cash at beginning of period	55,164	45,027	66,858
Cash, cash equivalents, and restricted cash at end of period	$ 61,367	$ 55,164	$ 45,027