Stock Option and Compensation Plans (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
$20.01-$30.00
Options Outstanding
Total Options Outstanding (in shares)	179
Weighted Average Remaining Life	8 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 25.64
Options Exercisable
Number Exercisable (in shares)	46
Weighted Average Exercise Price (in dollars per share)	$ 25.43
$30.01-$43.90
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 30.00
Exercise prices, high end of range (in dollars per share)	$ 43.90
Options outstanding
Options Outstanding
Total Options Outstanding (in shares)	3,680
Weighted Average Remaining Life	21 years 11 days
Aggregate Intrinsic Value	$ 87,728
Cash proceeds from, and the aggregate intrinsic value of, stock options exercised
Cash proceeds from options exercised	2,949	94	2
Aggregate intrinsic value of options exercised	21,646	4,545	28
Options Exercisable
Number Exercisable (in shares)	993
Weighted Average Exercise Price (in dollars per share)	$ 7.65
Aggregate Intrinsic Value	$ 36,965
Options outstanding | $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)	1,243
Weighted Average Remaining Life	7 years 1 month 6 days
Weighted Average Exercise Price (in dollars per share)	$ 5.67
Options Exercisable
Number Exercisable (in shares)	761
Weighted Average Exercise Price (in dollars per share)	$ 3.66
Options outstanding | $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)	534
Weighted Average Remaining Life	8 years 6 months
Weighted Average Exercise Price (in dollars per share)	$ 13.38
Options Exercisable
Number Exercisable (in shares)	132
Weighted Average Exercise Price (in dollars per share)	$ 13.39
Options outstanding | $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 | $30.01-$43.90
Options Outstanding
Total Options Outstanding (in shares)	1,724
Weighted Average Remaining Life	9 years 2 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 34.00
Options Exercisable
Number Exercisable (in shares)	54
Weighted Average Exercise Price (in dollars per share)	$ 34.79