Nature of Business and Significant Accounting Policies (Details Textual) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Years	Dec. 31, 2011	Dec. 31, 2010
Cumulative translation gain included in accumulated other comprehensive earnings	$ 14,700,000	$ (6,100,000)
Gains and (losses) netted against other income, net	(3,000,000)	(1,100,000)	(700,000)
Carrying value of demonstration units	33,500,000	32,400,000
Advertising costs	8,500,000	11,100,000	9,200,000
Carrying value of cost-basis investments	13,500,000	10,500,000
Effect of stock-based compensation awards, shares excluded for purposes of diluted earnings per share	1,198	352	418
Unrecognized stock-based compensation costs, net of estimated forfeitures	37,100,000
Weighted average period of unrecognized stock-based compensation costs, net of estimated forfeitures	2.0
Estimated forfeiture rate	5.00%
Cash received from the exercise of stock options	3,600,000	13,800,000	15,500,000
Related tax benefit realized from the exercise of the stock options	100,000	5,500,000	8,300,000
Level 1
Cash equivalents	5,900,000	192,600,000
Market-based restricted stock unit
Restricted stock units granted	795
Weighted average grant date fair value per share	$ 11.73
Total fair value of awards granted	9,300,000
Time-vested restricted stock unit
Restricted stock units granted	985	534	535
Performance-based restricted stock unit
Restricted stock units granted		101
Time-vested and performance-based restricted stock units
Weighted average grant date fair value per share	$ 21.66	$ 34.35	$ 29.91
Restricted stock units
Total fair value of awards granted	$ 30,660,000	$ 21,822,000	$ 16,011,000