Marketable Securities (Details 1) - USD ($) $ in Thousands	12 Months Ended
Dec. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,446,428	$ 1,509,924
Gross Unrealized Gains	262	587
Gross Unrealized Losses	(24,970)	(30,274)
Fair Value	1,421,720	1,480,237
U.S.Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,591	29,291
Gross Unrealized Gains		31
Gross Unrealized Losses	(254)	(288)
Fair Value	19,337	29,034
Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	44,191	60,513
Gross Unrealized Gains	1	19
Gross Unrealized Losses	(831)	(991)
Fair Value	43,361	59,541
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	180,470	236,354
Gross Unrealized Gains	13	41
Gross Unrealized Losses	(5,868)	(5,572)
Fair Value	174,615	230,823
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	830,447	914,028
Gross Unrealized Gains	136	252
Gross Unrealized Losses	(13,790)	(20,555)
Fair Value	816,793	893,725
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	187,999	178,804
Gross Unrealized Gains	110	224
Gross Unrealized Losses	(2,004)	(2,859)
Fair Value	186,105	176,169
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	183,730	90,934
Gross Unrealized Gains	2	20
Gross Unrealized Losses	(2,223)	(9)
Fair Value	$ 181,509	$ 90,945

This item represents the cost of debt 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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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