Nature of Business and Significant Accounting Policies (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ 26,506,000	$ 14,668,000
Gains and (losses) netted against other income, net	(300,000)	(3,000,000)	1,100,000
Carrying value of demonstration units	42,700,000	35,800,000
Advertising costs	10,700,000	8,500,000	11,100,000
Carrying value of cost-basis investments	13,500,000	13,500,000
Effect of stock-based compensation awards, shares excluded for purposes of diluted earnings per share	549,000	1,198,000	352,000
Unrecognized stock-based compensation costs, net of estimated forfeitures	42,700,000
Weighted average period of unrecognized stock-based compensation costs, net of estimated forfeitures	1 year 9 months 18 days
Estimated forfeiture rate	5.00%
Level 1
Cash Equivalents, at Carrying Value	28,500,000	5,900,000
Time-vested restricted stock unit
Restricted stock units granted	1,173,000	985,000	534,000
Performance-based restricted stock unit
Restricted stock units granted			101,000
Time-vested and performance-based restricted stock unit
Weighted average grant date fair value per share	$ 23.98	$ 21.66	$ 34.35
Market-based restricted stock unit
Restricted stock units granted	7,000	795,000
Weighted average grant date fair value per share	$ 15.87	$ 11.73
Total fair value of awards granted	100,000	9,300,000
Restricted Stock Unit Awards
Total fair value of awards granted	28,200,000	30,660,000	21,822,000
Stock Option Awards
Weighted average grant date fair value per share	$ 5.92	$ 6.43	$ 11.61
Cash received from the exercise of stock options	4,600,000	3,600,000	13,800,000
Related tax benefit realized from the exercise of the stock options	600,000	100,000	5,500,000
Employee Severance [Member]
Prior Period Reclassification Adjustment		3,800,000	700,000
Demonstration units [Member]
Prior Period Reclassification Adjustment		$ 2,300,000