Investments (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Available For Sale Debt Securities

Following is a summary of debt securities as of June 30, 2018 and December 30, 2017:

	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(Amounts are in thousands)
June 30, 2018
Tax exempt bonds	$	1,498,690		189		15,898	1,482,981
Taxable bonds	2,229,148			335		60,235	2,169,248
	$	3,727,838		524		76,133	3,652,229
December 30, 2017
Tax exempt bonds	$	1,811,523		602		16,420	1,795,705
Taxable bonds	2,115,174			695		25,443	2,090,426
	$	3,926,697		1,297		41,863	3,886,131

Amortized Cost and Fair Value of Available For Sale Debt Securities by Expected Maturity

The cost and fair value of debt securities by expected maturity as of June 30, 2018 and December 30, 2017 are as follows:

	June 30, 2018			December 30, 2017
	Cost		Fair Value	Cost	Fair Value
	(Amounts are in thousands)
Due in one year or less	$	667,148	665,338	917,576	915,579
Due after one year through five years	2,771,861		2,701,701	2,794,099	2,757,504
Due after five years through ten years	276,032		272,281	205,792	203,533
Due after ten years	12,797		12,909	9,230	9,515
	$	3,727,838	3,652,229	3,926,697	3,886,131

Temporarily Impaired Available For Sale Debt Securities by Time Period Impaired

Following is a summary of temporarily impaired debt securities by the time period impaired as of June 30, 2018 and December 30, 2017:

	Less Than 12 Months				12 Months or Longer			Total
	Fair Value		Unrealized Losses		Fair Value	Unrealized Losses		Fair Value	Unrealized Losses
	(Amounts are in thousands)
June 30, 2018
Tax exempt bonds	$	1,335,920		13,364	122,314		2,534	1,458,234		15,898
Taxable bonds	1,158,976			22,465	938,835		37,770	2,097,811		60,235
	$	2,494,896		35,829	1,061,149		40,304	3,556,045		76,133
December 30, 2017
Tax exempt bonds	$	1,543,151		13,827	136,217		2,593	1,679,368		16,420
Taxable bonds	811,886			4,908	1,153,645		20,535	1,965,531		25,443
	$	2,355,037		18,735	1,289,862		23,128	3,644,899		41,863

Equity Securities [Table Text Block]

Following is a summary of the fair value of equity securities as of June 30, 2018 and December 30, 2017:

	June 30, 2018			December 30, 2017
	(Amounts are in thousands)
Equity securities		$	2,815,353		2,383,095
Restricted investment		161,307			164,085
		$	2,976,660		2,547,180

Investment Income [Table Text Block]

Following is a summary of investment income for the three and six months ended June 30, 2018 and July 1, 2017:

		Three Months Ended						Six Months Ended
	June 30, 2018				July 1, 2017		June 30, 2018			July 1, 2017
	(Amounts are in thousands)
Interest income		$	19,762			20,908		38,256			42,047
Dividend income		11,299				9,529		21,897			17,870
Net realized gain on sale of investments		16,642				63,289		23,667			94,558
		47,703				93,726		83,820			154,475
Fair value adjustment (net unrealized gain) on equity securities held at end of period		76,829				—		51,047			—
Net gain on sale of equity securities previously recognized through fair value adjustment		(16,217		)		—		(22,414	)		—
		$	108,315			93,726		112,453			154,475