Long-Term Debt and Capital Leases (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Jan. 01, 2012
Long-Term Debt and Capital Leases (Textual) [Abstract]
Credit agreement provides for facility fees Minimum	0.20%
Credit agreement provides for facility fees Maximum	0.45%
Total capital leases	$ 14.7	$ 14.8
Capital leases, current	1.6	1.4
Available borrowings capacity under letters of credit	169.9
Available capacity under credit facility	550.0
Letter of Credit [Member]
Long-Term Debt and Capital Leases (Additional Textual) [Abstract]
Uncommitted credit line facility amount outstanding	0	0
Uncommitted credit line permits extensions for standby letters of credit	5.0
Incremental line of credit for standby letters of credit	2.0
Letter of credit, outstanding	$ 13.4
4.04% Senior Notes due September 2015 [Member]
Long-Term Debt and Capital Leases (Additional Textual) [Abstract]
Interest Rate, Stated Percentage	4.04%
4.74% Senior Notes due September 2017 [Member]
Long-Term Debt and Capital Leases (Additional Textual) [Abstract]
Interest Rate, Stated Percentage	4.74%
5.30% Senior Notes due September 2020 [Member]
Long-Term Debt and Capital Leases (Additional Textual) [Abstract]
Interest Rate, Stated Percentage	5.30%
$550.0 million revolving credit facility [Member]
Long-Term Debt and Capital Leases (Additional Textual) [Abstract]
Weighted Average rate under credit facility	1.68%	2.48%