Stock Option and Compensation Plans (Details 2) (Stock options, USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Options Outstanding
Total Options Outstanding (in shares)	3,796
Aggregate Intrinsic Value	$ 84,600
Options Exercisable
Number Exercisable (in shares)	1,160
Aggregate Intrinsic Value	$ 37,497
$0.12-$10.03
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 0.12
Exercise prices, high end of range (in dollars per share)	$ 10.03
Options Outstanding
Total Options Outstanding (in shares)	1,057
Weighted Average Remaining Life	6 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 5.85
Options Exercisable
Number Exercisable (in shares)	639
Weighted Average Exercise Price (in dollars per share)	$ 3.77
$10.04-$20.00
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 10.04
Exercise prices, high end of range (in dollars per share)	$ 20.00
Options Outstanding
Total Options Outstanding (in shares)	495
Weighted Average Remaining Life	8 years
Weighted Average Exercise Price (in dollars per share)	$ 13.39
Options Exercisable
Number Exercisable (in shares)	128
Weighted Average Exercise Price (in dollars per share)	$ 13.44
$20.01-$30.00
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 20.01
Exercise prices, high end of range (in dollars per share)	$ 30.00
Options Outstanding
Total Options Outstanding (in shares)	176
Weighted Average Remaining Life	8 years 7 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 25.64
Options Exercisable
Number Exercisable (in shares)	55
Weighted Average Exercise Price (in dollars per share)	$ 25.49
$30.01-$40.00
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 30.01
Exercise prices, high end of range (in dollars per share)	$ 40.00
Options Outstanding
Total Options Outstanding (in shares)	1,595
Weighted Average Remaining Life	9 years
Weighted Average Exercise Price (in dollars per share)	$ 33.59
Options Exercisable
Number Exercisable (in shares)	338
Weighted Average Exercise Price (in dollars per share)	$ 32.36
$40.01 - $53.95
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 40.01
Exercise prices, high end of range (in dollars per share)	$ 53.95
Options Outstanding
Total Options Outstanding (in shares)	473
Weighted Average Remaining Life	9 years 8 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 45.63