Stock Compensation Shares Authorized under Stock Option Plans by Exercise Price Range (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding (in shares)	3,745,631	3,454,292.000	3,469,825.000		2,645,914
Outstanding, Weighted Average Remaining Contractual Term	5 years 10 months 24 days	6 years 4 months 24 days	6 years 6 months 18 days	6 years 7 months 6 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 13.82	$ 12.77	$ 11.98		$ 11.33
Options exercisable (in shares)	2,035,345	1,598,885	1,959,317
Exercisable, Weighted-Average Remaining Contractual Life (Years)	4 years 2 months 12 days
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.30
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 25,024
Exercise Price Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 0.00
Range of Exercise Prices, Maximum (in dollars per share)	$ 11.00
Options Outstanding (in shares)	1,500,905
Outstanding, Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 10.52
Options exercisable (in shares)	1,500,905
Exercisable, Weighted-Average Remaining Contractual Life (Years)	3 years 10 months 24 days
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 10.52
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0
Exercise Price Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 11.00
Range of Exercise Prices, Maximum (in dollars per share)	$ 13.20
Options Outstanding (in shares)	31,906
Outstanding, Weighted Average Remaining Contractual Term	5 years 1 month 6 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.46
Options exercisable (in shares)	23,928
Exercisable, Weighted-Average Remaining Contractual Life (Years)	5 years 1 month 6 days
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.46
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0
Exercise Price Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 13.20
Range of Exercise Prices, Maximum (in dollars per share)	$ 15.40
Options Outstanding (in shares)	1,378,728
Outstanding, Weighted Average Remaining Contractual Term	6 years 4 months 24 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 13.78
Options exercisable (in shares)	510,512
Exercisable, Weighted-Average Remaining Contractual Life (Years)	5 years
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 13.52
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0
Exercise Price Range Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 15.40
Range of Exercise Prices, Maximum (in dollars per share)	$ 17.60
Options Outstanding (in shares)	0
Outstanding, Weighted Average Remaining Contractual Term	0 years
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 0.00
Options exercisable (in shares)	0
Exercisable, Weighted-Average Remaining Contractual Life (Years)	0 years
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.00
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0
Exercise Price Range Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 17.60
Range of Exercise Prices, Maximum (in dollars per share)	$ 19.80
Options Outstanding (in shares)	427,217
Outstanding, Weighted Average Remaining Contractual Term	8 years 4 months 24 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17.82
Options exercisable (in shares)	0
Exercisable, Weighted-Average Remaining Contractual Life (Years)	0 years
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.00
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0
Exercise Price Range Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 19.80
Range of Exercise Prices, Maximum (in dollars per share)	$ 22.00
Options Outstanding (in shares)	406,875
Outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 12 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 22.00
Options exercisable (in shares)	0
Exercisable, Weighted-Average Remaining Contractual Life (Years)	0 years
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.00
Options Exercisable, Weighted Aggregate Intrinsic Value	$ 0