Condensed Consolidated Statements of Equity - USD ($) $ in Thousands	Total		Common Shares	Additional Paid-in Capital	Treasury Shares	Accumulated Other Comprehensive Income (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)	(27,135)						(27,208)	73
Other comprehensive income (loss)	2,786	[1]				2,786
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) (134 shares) and ($323) (122 shares)	5,325			899	4,426
Dividends declared ($0.495 and $0.32 per common share)	(13,503)						(13,503)
Restricted share award dividend equivalents	0			5	52		(57)
Ending Balance at Sep. 30, 2017	749,811		96	223,814	(40,905)	(9,682)	568,438	8,050
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)	17,557						17,732	(175)
Other comprehensive income (loss)	(1,664)	[1]				(1,664)
Cash received from (paid to) noncontrolling interest	21,116			(2,268)				23,384
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of ($0) (134 shares) and ($323) (122 shares)	5,167			14	5,153
Adoption of accounting standard, net of income tax of $2,869	(8,441)						(8,441)
Dividends declared ($0.495 and $0.32 per common share)	(13,991)						(13,991)
Restricted share award dividend equivalents	0				120		(120)
Ending Balance at Sep. 30, 2018	$ 842,643		$ 96	$ 222,368	$ (35,039)	$ (4,364)	$ 628,676	$ 30,906

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