Investments and Fair Value Measurements-AFS Investments (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 30, 2012
Fixed Income Securities [Member]
Available-for-sale investments
Amortized Cost	$ 5,153,393	$ 4,920,082
Gross Unrealized Gain	32,208	27,111
Gross Unrealized Loss	(424)	(1,868)
Fair Value	5,185,177	4,945,325
U.S. Treasury and government agency securities [Member]
Available-for-sale investments
Amortized Cost	65,727	27,377
Gross Unrealized Gain	13	9
Gross Unrealized Loss	0	0
Fair Value	65,740	27,386
U.S. Government-sponsored agency securities [Member]
Available-for-sale investments
Amortized Cost	23,525	28,339
Gross Unrealized Gain	36	41
Gross Unrealized Loss	(1)	(1)
Fair Value	23,560	28,379
International Government Securities [Member]
Available-for-sale investments
Amortized Cost	17,093	153,936
Gross Unrealized Gain	1	13
Gross Unrealized Loss	(15)	(3)
Fair Value	17,079	153,946
Corporate notes and bonds [Member]
Available-for-sale investments
Amortized Cost	847,920	864,170
Gross Unrealized Gain	3,434	3,890
Gross Unrealized Loss	(69)	(938)
Fair Value	851,285	867,122
Asset-backed securities [Member]
Available-for-sale investments
Amortized Cost	184,368	179,356
Gross Unrealized Gain	225	453
Gross Unrealized Loss	(43)	0
Fair Value	184,550	179,809
Mortgage-backed securities [Member]
Available-for-sale investments
Amortized Cost	1,703	1,872
Gross Unrealized Gain	0	8
Gross Unrealized Loss	(22)	(14)
Fair Value	1,681	1,866
Municipal notes and bonds [Member]
Available-for-sale investments
Amortized Cost	4,013,057	3,665,032
Gross Unrealized Gain	28,499	22,697
Gross Unrealized Loss	(274)	(912)
Fair Value	$ 4,041,282	$ 3,686,817

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

Amount of debt securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 137

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 320

-Section 50

-Paragraph 2

-Subparagraph (b)-(g)

-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details