Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock-Based Compensation
Stock-based compensation expense recognized related to stock compensation plans	$ 3,100	$ 2,900	$ 10,200	$ 9,100
Assumptions used to determine fair value of options granted
Weighted-average grant-date fair value per share of the stock options granted	$ 3.80	$ 7.24
Expected life			4 years 10 months 24 days	4 years 9 months 22 days
Additional disclosures
Proceeds from exercise of stock options			$ 4,188	$ 3,279
Tax benefit from exercise of stock options	$ 21,000		1,477
Stock options
Stock-Based Compensation
Stock-based compensation expense recognized related to stock compensation plans	$ 1,400	$ 1,700	$ 4,500	$ 5,300
Stock option activity
Options outstanding at the beginning of the period (in shares)			4,101,000
Granted (in shares)			1,274,000
Exercised (in shares)	(105,462)	(36,016)	(577,559)	(352,057)
Forfeitures (in shares)			(518,000)
Expired (in shares)			(317,000)
Options outstanding at the end of the period (in shares)	3,962,000		3,962,000
Options expected to vest at the end of the period (in shares)	2,410,000		2,410,000
Options exercisable at the end of the period (in shares)	1,498,000		1,498,000
Stock options, Weighted Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)			$ 18.72
Granted (in dollars per share)			16.67
Exercised (in dollars per share)			7.25
Forfeitures (in dollars per share)			21.61
Expired (in dollars per shares)			24.75
Options outstanding at the end of the period (in dollars per share)	$ 18.88		18.88
Options expected to vest at the end of the period (in dollars per share)	19.48		19.48
Options exercisable at the end of the period (in dollars per share)	$ 17.87		$ 17.87
Stock options, Weighted Average Remaining Contractual Terms
Options outstanding at the end of the period			4 years 9 months 26 days
Options expected to vest at the end of the period			5 years 10 months 28 days
Options exercisable at the end of the period			3 years 11 days
Stock options, Aggregate Intrinsic Value
Options outstanding at the end of the period	$ 1,794		$ 1,794
Options exercisable at the end of the period	1,794		$ 1,794
Assumptions used to determine fair value of options granted
Risk-free interest rate (as a percent)			1.55%	1.56%
Expected volatility (as a percent)			41.77%	38.11%
Additional disclosures
Proceeds from exercise of stock options	800	$ 100	$ 4,200	$ 3,300
Tax benefit from exercise of stock options		17,000	1,500	900
Unrecognized stock-based compensation, stock options	11,100		$ 11,100
Weighted-average period over which compensation will be recognized			1 year 1 month 28 days
Total intrinsic value of options exercised	$ 200	$ 600	$ 5,900	$ 3,900