Stock-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized under plan	2,500,000
Total intrinsic value	$ 3,845,000
Weighted average grant date fair value of shares granted (in dollars per share)	$ 14.62	[1]
Stock compensation	11,100,000		9,600,000	9,200,000
Stock-based compensation cost recognized, retirement savings plan contributions	1,700,000		1,400,000	1,100,000
Associated current and future income tax benefit recognized	3,600,000		3,200,000	3,100,000
Unrecognized compensation cost related to non-vested share-based awards	15,600,000
Unrecognized compensation cost, weighted-average period for recognition	2 years
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum fair value of common stock under ESPP	25,000
Annual participation limit	12,500
Shares purchased under the ESPP (in shares)	9,600
ESPP purchase price, percentage of fair market value (in hundredths)	95.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term of stock options	10 years
Total intrinsic value			400,000	5,600,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of shares granted (in dollars per share)			$ 11.31	$ 10.31
Fair value of shares vested	$ 13,400,000		$ 9,700,000	$ 7,800,000
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period	3 years
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period	5 years

[1] The weighted average grant date fair value of shares granted during 2012 and 2011 was $11.31 and $10.31, respectively.