Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Total		Common Shares	Additional Paid-in Capital	Treasury Shares	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interests
Beginning Balance at Dec. 31, 2016	$ 790,697		$ 96	$ 222,910	$ (45,383)	$ (12,468)	$ 609,206	$ 16,336
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(29,752)						(29,742)	(10)
Other comprehensive income (loss)	475	[1]				475
Other change in noncontrolling interest	(8,359)							(8,359)
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of ($0) (105 shares) and ($323) (126 shares)	3,732			(654)	4,386
Dividends declared ($0.16 and $0.165 per common share)	(9,001)						(9,001)
Restricted share award dividend equivalents	0			5	52		(57)
Ending Balance at Jun. 30, 2017	747,792		96	222,261	(40,945)	(11,993)	570,406	7,967
Beginning Balance at Dec. 31, 2017	822,899		96	224,622	(40,312)	(2,700)	633,496	7,697
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	19,431						19,829	(398)
Other comprehensive income (loss)	(2,647)	[1]				(2,647)
Cash received from noncontrolling interest	21,806							21,806
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of ($0) (105 shares) and ($323) (126 shares)	3,268			(1,363)	4,631
Adoption of accounting standard, net of income tax of $2,869	(8,441)						(8,441)
Dividends declared ($0.16 and $0.165 per common share)	(9,326)						(9,326)
Restricted share award dividend equivalents	0				120		(120)
Ending Balance at Jun. 30, 2018	$ 846,990		$ 96	$ 223,259	$ (35,561)	$ (5,347)	$ 635,438	$ 29,105

[1] All amounts are net of tax. Amounts in parentheses indicate debits