CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Issued	Common Stock Treasury	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standards (See Note 2)	$ 397			$ 1,106	$ (709)
Balances at Dec. 31, 2016	137,563	$ 140,625	$ (760,391)	172,101	1,150,688	$ (606,722)	$ 41,262
Increase (Decrease) in Stockholders' Equity
Net income	43,664				41,226		2,438
Cash dividends declared: noncontrolling interests	(1,783)						(1,783)
Sale of subsidiary shares to noncontrolling interest	(3,412)			(2,242)			(1,170)
Total other comprehensive income (loss), net of deferred income taxes of $(4,131) and $2,913 in 2018 and 2017, respectively	27,406					25,171	2,235
Stock Appreciation Rights exercised, net 27,669 shares and 8,965 shares in 2018 and 2017, respectively	(63)	16	(63)	(16)
Vesting of restricted stock units and other stock grants, net 382,228 shares and 260,497 shares in 2018 and 2017, respectively	(1,544)	452	(1,544)	(452)
Amortization of unearned portion of stock-based compensation, net of forfeitures	7,790			7,790
Balances at Sep. 30, 2017	210,018	141,093	(761,998)	178,287	1,191,205	(581,551)	42,982
Balances at Dec. 31, 2017	215,165	141,110	(762,079)	180,201	1,157,801	(546,582)	44,714
Increase (Decrease) in Stockholders' Equity
Net income	96,939				91,144		5,795
Cash dividends declared: noncontrolling interests	(5,534)						(5,534)
Sale of subsidiary shares to noncontrolling interest	477						477
Total other comprehensive income (loss), net of deferred income taxes of $(4,131) and $2,913 in 2018 and 2017, respectively	(9,801)					(7,189)	(2,612)
Stock Appreciation Rights exercised, net 27,669 shares and 8,965 shares in 2018 and 2017, respectively	(273)	49	(273)	(49)
Vesting of restricted stock units and other stock grants, net 382,228 shares and 260,497 shares in 2018 and 2017, respectively	(3,413)	678	(3,413)	(678)
Amortization of unearned portion of stock-based compensation, net of forfeitures	8,456			8,456
Balances at Sep. 30, 2018	$ 304,391	$ 141,837	$ (765,765)	$ 187,930	1,252,840	$ (555,291)	$ 42,840
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standards (See Note 2)					$ 100