Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 1,023,513	$ 1,036,273	$ 1,090,630
Cost of sales	506,292	536,109	579,825
Gross profit	517,221	500,164	510,805
Selling, general and administrative expenses	494,601	503,174	567,823
Asset impairments	5,284	3,144	15,306
Income (loss) from operations	17,336	(6,154)	(72,324)
Foreign currency gain (loss), net	563	(2,454)	(3,332)
Interest income	870	692	967
Interest expense	(869)	(836)	(969)
Other income, net	280	1,539	914
Income (loss) before income taxes	18,180	(7,213)	(74,744)
Income tax expense	7,942	9,281	8,452
Net income (loss)	10,238	(16,494)	(83,196)
Dividends on Series A convertible preferred stock	(12,000)	(12,000)	(11,833)
Dividend equivalents on Series A convertible preferred shares related to redemption value accretion and beneficial conversion feature	(3,532)	(3,244)	(2,978)
Net loss attributable to common stockholders	$ (5,294)	$ (31,738)	$ (98,007)
Net loss per common share:
Basic (in dollars per share)	$ (0.07)	$ (0.43)	$ (1.30)
Diluted (in dollars per share)	$ (0.07)	$ (0.43)	$ (1.30)
Weighted average common shares outstanding:
Weighted average common shares outstanding - basic (shares)	72,255	73,371	75,604
Weighted average common shares outstanding - diluted (shares)	72,255	73,371	75,604