Debt - LT Debt (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term debt	$ 2,072,625		$ 2,072,625		$ 1,587,478
Net proceeds from note offering			591,156	0
Loss on prepayment of debt	0	0	(4,277)	0
Loss on prepayment of debt, net of tax			(2,627)	0
Loss on prepayment of debt, net of tax per share on a basic basis			$ 0.03
Loss on prepayment of debt, net of tax per share on a diluted basis			$ 0.02
Accounts receivable, net	4,723,601		4,723,601		4,923,898
Investment Income, Interest and Dividend	549	650	1,120	1,235
Revolving credit facility [Member]
Debt Instrument [Line Items]
Long-term debt	63,300		63,300		123,600
Line of Credit Facility, Maximum Borrowing Capacity	1,200,000		1,200,000
Debt Instrument, Basis Spread on Variable Rate	1.275%		1.275%
Debt Instrument, Interest Rate, Effective Percentage	1.49%		1.49%
Line of Credit Facility, Commitment Fee Percentage	0.225%
Asset securitization program [Member]
Debt Instrument [Line Items]
Long-term debt	200,000		200,000		225,000
Asset Securitization Program Maximum Capacity	775,000		775,000
Asset Securitization Program Interest Rate Spread At End of Period	0.40%		0.40%
Debt Instrument, Interest Rate, Effective Percentage	0.70%		0.70%
Asset Securitization Program Facility Fee	0.40%		0.40%
Accounts receivable, net	1,558,100		1,558,100		1,610,946
6.875% senior notes, due 2013 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.875%		6.875%
Debt Instrument, Fair Value	0		0		342,000
Redemption of Senior Notes, principal amount			332,107
3.375% notes, due 2015 [Member]
Debt Instrument [Line Items]
Long-term debt	256,368		256,368		257,732
Debt Instrument, Interest Rate, Stated Percentage	3.375%		3.375%
Debt Instrument, Fair Value	260,000		260,000		260,000
6.875% senior debentures, due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	198,974		198,974		198,869
Debt Instrument, Interest Rate, Stated Percentage	6.875%		6.875%
Debt Instrument, Fair Value	230,000		230,000		236,000
3.00% notes, due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	298,546		298,546		0
Debt Instrument, Interest Rate, Stated Percentage	3.00%		3.00%
Debt Instrument, Fair Value	300,000		300,000		0
Principal Amount of Issuance of Long-term Debt			300,000
6.00% notes, due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	299,940		299,940		299,936
Debt Instrument, Interest Rate, Stated Percentage	6.00%		6.00%
Debt Instrument, Fair Value	333,000		333,000		342,000
5.125% notes, due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	249,396		249,396		249,356
Debt Instrument, Interest Rate, Stated Percentage	5.125%		5.125%
Debt Instrument, Fair Value	262,500		262,500		272,500
4.50% notes, due 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	297,672		297,672		0
Debt Instrument, Interest Rate, Stated Percentage	4.50%		4.50%
Debt Instrument, Fair Value	294,000		294,000		0
Principal Amount of Issuance of Long-term Debt			300,000
7.5% senior debentures, due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	198,100		198,100		198,030
Debt Instrument, Interest Rate, Stated Percentage	7.50%		7.50%
Debt Instrument, Fair Value	230,000		230,000		246,000
Other obligations with various interest rates and due dates [Member]
Debt Instrument [Line Items]
Long-term debt	$ 10,329		$ 10,329		$ 34,955