Consolidated Statements of Stockholders' Equity Consolidated Stockholders' Equity - USD ($)	Total	Retained Earnings [Member]	Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]	Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]	Additional Paid-in Capital [Member]	Treasury Stock, Common [Member]	Common Stock [Member] Additional Paid-in Capital [Member]
Common Stock, Shares, Outstanding	49,669,848
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 51,000
Capital in excess of par value	851,280,000
Treasury Stock, Value	(179,082,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(367,870,000)
Retained Earnings (Accumulated Deficit)	146,155,000
Total stockholders' equity at Mar. 31, 2018	450,534,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(76,534,000)	$ (76,534,000)
Foreign currency translation adjustment	(14,524,000)
Other Comprehensive Income (Loss), Net of Tax			$ (399,000)	$ (1,035,000)
Dividends, Common Stock, Cash	(1,988,000)	(1,988,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	102,248
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 2,464,000				$ (84,000)
Treasury Stock Reissued at Lower than Repurchase Price					(644,000)	$ (2,548,000)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(23,756)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (532,000)					532,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	16,020
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 384,000					1,028,000
Total stockholders' equity at Jun. 30, 2018	(226,581,000)
Net Income (Loss) Attributable to Parent	(122,155,000)
Total stockholders' equity at Mar. 31, 2018	450,534,000
Foreign currency translation adjustment	(21,211,000)
Other Comprehensive Income (Loss), Net of Tax	(22,759,000)
Total stockholders' equity at Dec. 31, 2018	$ (276,497,000)
Common Stock, Shares, Outstanding	49,764,360
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 51,000
Capital in excess of par value	850,552,000
Treasury Stock, Value	(176,038,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(383,828,000)
Retained Earnings (Accumulated Deficit)	(517,318,000)
Total stockholders' equity at Jun. 30, 2018	(226,581,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(14,676,000)	(14,676,000)
Foreign currency translation adjustment	1,038,000
Other Comprehensive Income (Loss), Net of Tax			(399,000)	964,000
Dividends, Common Stock, Cash	(1,993,000)	(1,993,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	31,596
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 3,266,000				2,671,000
Treasury Stock Reissued at Lower than Repurchase Price					(821,000)	(595,000)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(857)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (16,000)					16,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	17,618
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 327,000					1,148,000
Total stockholders' equity at Sep. 30, 2018	$ (238,051,000)
Common Stock, Shares, Outstanding	49,812,717
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 51,000
Capital in excess of par value	852,402,000
Treasury Stock, Value	(174,311,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(382,225,000)
Retained Earnings (Accumulated Deficit)	(533,968,000)
Net Income (Loss) Attributable to Parent	(30,945,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(30,945,000)	(30,945,000)
Foreign currency translation adjustment	(7,725,000)
Other Comprehensive Income (Loss), Net of Tax	(8,404,000)		(399,000)	(280,000)
Dividends, Common Stock, Cash	(1,994,000)	(1,994,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	25,524
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 2,757,000				1,077,000
Treasury Stock Reissued at Lower than Repurchase Price					(636,000)	(1,680,000)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(4,735)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (97,000)					97,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	14,567
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 321,000					957,000
Total stockholders' equity at Dec. 31, 2018	$ (276,497,000)
Common Stock, Shares, Outstanding	49,848,073
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 51,000
Capital in excess of par value	852,843,000
Treasury Stock, Value	(171,771,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(390,629,000)
Retained Earnings (Accumulated Deficit)	$ (566,991,000)
Common Stock, Shares, Outstanding	49,887,268
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 52,000
Capital in excess of par value	867,545,000
Treasury Stock, Value	(159,154,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(487,684,000)
Retained Earnings (Accumulated Deficit)	(794,072,000)
Total stockholders' equity at Mar. 31, 2019	(573,313,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	18,088,000	18,088,000
Foreign currency translation adjustment	(2,683,000)
Other Comprehensive Income (Loss), Net of Tax			1,409,000	(319,000)
Dividends, Common Stock, Cash	(1,998,000)	(1,998,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	154,802
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 1,903,000				(7,631,000)
Treasury Stock Reissued at Lower than Repurchase Price					(634,000)	(9,534,000)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(51,406)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (1,043,000)					1,043,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	14,489
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 262,000					896,000
Total stockholders' equity at Jun. 30, 2019	(557,919,000)
Net Income (Loss) Attributable to Parent	46,943,000
Total stockholders' equity at Mar. 31, 2019	(573,313,000)
Foreign currency translation adjustment	2,164,000
Other Comprehensive Income (Loss), Net of Tax	(57,615,000)
Total stockholders' equity at Dec. 31, 2019	$ (532,897,000)
Common Stock, Shares, Outstanding	50,005,153
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 52,000
Capital in excess of par value	859,280,000
Treasury Stock, Value	(149,767,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(489,277,000)
Retained Earnings (Accumulated Deficit)	(778,207,000)
Total stockholders' equity at Jun. 30, 2019	(557,919,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	42,701,000	42,701,000
Foreign currency translation adjustment	(6,227,000)
Other Comprehensive Income (Loss), Net of Tax			(69,319,000)	(1,078,000)
Dividends, Common Stock, Cash	(2,003,000)	(2,003,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	59,938
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 2,804,000				(850,000)
Treasury Stock Reissued at Lower than Repurchase Price					(400,000)	(3,654,000)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(764)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (5,000)					5,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	10,196
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 222,000					622,000
Total stockholders' equity at Sep. 30, 2019	$ (590,824,000)
Common Stock, Shares, Outstanding	50,074,523
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 52,000
Capital in excess of par value	858,030,000
Treasury Stock, Value	(145,496,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(565,901,000)
Retained Earnings (Accumulated Deficit)	(737,509,000)
Net Income (Loss) Attributable to Parent	(13,846,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (13,846,000)	0
Stock Issued During Period, Shares, Employee Benefit Plan	1,730,703
Foreign currency translation adjustment	$ 11,074,000
Other Comprehensive Income (Loss), Net of Tax	20,602,000		$ 5,027,000	$ 4,501,000
Dividends, Common Stock, Cash	(2,004,000)	$ (2,004,000)
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	18,723
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	$ 3,068,000				1,927,000
Treasury Stock Reissued at Lower than Repurchase Price					$ (428,000)	(1,141,000)	$ 55,396,000
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(5,092)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ (131,000)					131,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	10,917
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 238,000					666,000
Total stockholders' equity at Dec. 31, 2019	(532,897,000)
Stock Issued During Period, Value, Treasury Stock Reissued						$ 105,396,000
Stock Issued During Period, Value, Employee Benefit Plan	$ 50,000,000
Common Stock, Shares, Outstanding	51,829,774
Common stock, $.001 par value, 100,000,000 shares authorized, 52,460,920 and 52,460,920 shares issued; 50,074,523 and 49,887,268 shares outstanding	$ 52,000
Capital in excess of par value	804,133,000
Treasury Stock, Value	(38,424,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(545,299,000)
Retained Earnings (Accumulated Deficit)	$ (753,359,000)