Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under employee stock purchase plan (in shares)	3,250,000
Shares available for grant or issuance under share-based compensation plans (in shares)	1,849,266
Compensation expense to be recognized	$ 6,600
Maximum vesting period	4 years
Proceeds from exercise of stock options	$ 3,800	$ 6,900	$ 5,200
Income tax benefit realized from exercise of stock options	1,600	8,600	5,200
Excess tax benefits from share-based compensation	1,663	8,264	4,624
Total intrinsic value of options exercised	$ 4,600	$ 23,500	$ 12,500
Options that were exercisable (in shares)	306,726	566,774	1,310,697
Weighted average exercise price of exercisable options (in dollars per share)	$ 23.42	$ 24.15	$ 18.12
Total intrinsic value of options outstanding and exercisable	$ 7,600	$ 11,500	$ 31,900
Awards of Shares and Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 8,800	$ 8,100	$ 6,900
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	0	0	0
Compensation expense	$ 0	$ 0	$ 0
Options outstanding	306,726	566,774	1,310,697	1,796,377
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested, but issuance deferred (in shares)	93,399
Issuance deferral period	5 years
Employee Stock Purchase Plan (in shares)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under employee stock purchase plan (in shares)	3,000,000