Stock-Based Compensation - Exercise Price Range (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number Outstanding	650	924	1,412	1,502
Options Outstanding - Weighted-Average Remaining Years of Contractual Life	5 years 7 months 2 days	6 years 1 month 3 days	4 years 10 months 28 days
Options Outstanding - Weighted-Average Exercise Price	$ 25.56	$ 22.04	$ 20.56	$ 19.53
Options Exercisable - Number Exercisable	421	671	1,181
Options Exercisable - Weighted-Average Exercise Price	$ 23.84	$ 22.62	$ 20.24
$16.64 to $17.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 16.64
Range of Exercise Prices, Upper Range Limit	$ 17.60
Options Outstanding - Number Outstanding	9
Options Outstanding - Weighted-Average Remaining Years of Contractual Life	0 years 4 months 20 days
Options Outstanding - Weighted-Average Exercise Price	$ 17.43
Options Exercisable - Number Exercisable	9
Options Exercisable - Weighted-Average Exercise Price	$ 17.43
18.25 to 21.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 18.25
Range of Exercise Prices, Upper Range Limit	$ 21.95
Options Outstanding - Number Outstanding	319
Options Outstanding - Weighted-Average Remaining Years of Contractual Life	6 years 5 months 8 days
Options Outstanding - Weighted-Average Exercise Price	$ 20.17
Options Exercisable - Number Exercisable	223
Options Exercisable - Weighted-Average Exercise Price	$ 20.42
24.91 to 29.25
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 24.91
Range of Exercise Prices, Upper Range Limit	$ 29.25
Options Outstanding - Number Outstanding	184
Options Outstanding - Weighted-Average Remaining Years of Contractual Life	4 years 0 months 14 days
Options Outstanding - Weighted-Average Exercise Price	$ 28.00
Options Exercisable - Number Exercisable	184
Options Exercisable - Weighted-Average Exercise Price	$ 28.00
35.28 to 35.35
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 35.28
Range of Exercise Prices, Upper Range Limit	$ 35.35
Options Outstanding - Number Outstanding	138
Options Outstanding - Weighted-Average Remaining Years of Contractual Life	6 years 0 months 3 days
Options Outstanding - Weighted-Average Exercise Price	$ 35.28
Options Exercisable - Number Exercisable	5
Options Exercisable - Weighted-Average Exercise Price	$ 35.35