Statement of Shareholders' Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Common Stock, Shares, Outstanding at Dec. 31, 2014		45,600,002				1,963,018
Common Stock, Value, Issued at Dec. 31, 2014	$ 93,993,000	$ 1,174,000	$ 0	$ 415,906,000	$ (11,894,000)	$ (317,613,000)	$ 6,420,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0				(183,455)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	21,279,000	$ 0	3,267,000	(11,044,000)	0	$ 29,056,000	0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(175,000)	0	(175,000)	0	0	0	0
Stock Repurchased During Period, Value	(159,709,000)	$ 0	0	0	0	$ (159,709,000)	0
Stock Repurchased During Period, Shares		0				1,444,534
Dividends	(94,235,000)	$ 0	0	(94,235,000)	0	$ 0
Proceeds from Issuance of Common Stock	0
Treasury Stock, Retired, Cost Method, Amount	0	$ (32,000)	(3,092,000)	(206,267,000)	0	$ 209,391,000	0
Treasury Stock, Shares, Retired		(1,250,000)				(1,250,000)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(1,140,000)	$ 0	0	0	0	$ 0	(1,140,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Net of Tax	(1,356,000)	0	0	0	1,356,000	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	114,932,000	0	0	114,847,000	0	0
Net Income (Loss) Attributable to Noncontrolling Interest	85,000						85,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	116,288,000
Common Stock, Value, Issued Period End at Dec. 31, 2015	(23,699,000)	$ 1,142,000	0	219,207,000	(10,538,000)	$ (238,875,000)	5,365,000
Common Stock, Shares, Outstanding Period End at Dec. 31, 2015		44,350,002				1,974,097
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0				(141,106)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	22,079,000	$ 0	(197,000)	0	0	$ 22,276,000	0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(1,162,000)	0	(1,162,000)	0	0	0	0
Stock Repurchased During Period, Value	(7,161,000)	$ 0	0	0	0	$ (7,161,000)	0
Stock Repurchased During Period, Shares		0				62,000
Dividends	(95,145,000)	$ 0	0	(95,145,000)	0	$ 0
Stock Issued During Period, Shares, New Issues		1,696,250				0
Proceeds from Issuance of Common Stock	197,202,000	$ 38,000	197,164,000	0	0	$ 0	0
Treasury Stock, Retired, Cost Method, Amount	0	$ (32,000)	(142,955,000)	0	0	$ 142,987,000	0
Treasury Stock, Shares, Retired		(1,250,000)				(1,250,000)
Stockholders' Equity, Other	(1,386,000)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders		$ 0	0	0	0	$ 0	(1,386,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Net of Tax	(710,000)	0	0	0	710,000	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	63,859,000	0	0	63,895,000	0	0
Net Income (Loss) Attributable to Noncontrolling Interest	(36,000)						(36,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	64,569,000
Common Stock, Value, Issued Period End at Dec. 31, 2016	$ 155,297,000	$ 1,148,000	52,850,000	187,957,000	(9,828,000)	$ (80,773,000)	3,943,000
Common Stock, Shares, Outstanding Period End at Dec. 31, 2016	44,151,261	44,796,252				644,991
Cumulative Effect on Retained Earnings, Net of Tax	$ 0	$ 0	84,000	(84,000)	0	$ 0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0				(191,513)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	22,942,000	$ 0	1,529,000	0	0	$ 21,413,000	0
Stock Repurchased During Period, Value	(16,909,000)	$ 0	0	0	0	$ (16,909,000)	0
Stock Repurchased During Period, Shares		0				158,569
Dividends	(97,143,000)	$ 0	0	(97,143,000)	0	$ 0
Proceeds from Issuance of Common Stock	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(26,000)	0	0	0	0	0	(26,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Other Comprehensive Income (Loss), Net of Tax	(1,475,000)	0	0	0	1,475,000	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	83,096,000	0	0	83,125,000	0	0
Net Income (Loss) Attributable to Noncontrolling Interest	(29,000)						(29,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	84,571,000
Common Stock, Value, Issued Period End at Dec. 31, 2017	$ 148,732,000	$ 1,148,000	$ 54,463,000	$ 173,855,000	$ (8,353,000)	$ (76,269,000)	$ 3,888,000
Common Stock, Shares, Outstanding Period End at Dec. 31, 2017	44,184,205	44,796,252				612,047