Investments (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Available For Sale Securities

Following is a summary of AFS securities as of December 31, 2016 and December 26, 2015:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(Amounts are in thousands)
2016
Tax exempt bonds	$	3,036,060		2,211		24,649	3,013,622
Taxable bonds	2,469,192			1,359		33,903	2,436,648
Restricted investments	164,548			—		463	164,085
Equity securities	1,021,340			110,879		7,956	1,124,263
	$	6,691,140		114,449		66,971	6,738,618
2015
Tax exempt bonds	$	3,336,841		12,038		2,737	3,346,142
Taxable bonds	2,214,366			1,492		10,399	2,205,459
Restricted investments	164,548			—		1,389	163,159
Equity securities	836,153			78,378		26,357	888,174
	$	6,551,908		91,908		40,882	6,602,934

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

The amortized cost and fair value of AFS securities by expected maturity as of December 31, 2016 and December 26, 2015 are as follows:

	2016			2015
	Amortized Cost		Fair Value	Amortized Cost	Fair Value
			(Amounts are in thousands)
Due in one year or less	$	1,592,144	1,591,740	1,375,450	1,376,698
Due after one year through five years	3,218,371		3,187,739	3,951,600	3,948,654
Due after five years through ten years	680,641		656,162	161,732	162,999
Due after ten years	14,096		14,629	62,425	63,250
	5,505,252		5,450,270	5,551,207	5,551,601
Restricted investments	164,548		164,085	164,548	163,159
Equity securities	1,021,340		1,124,263	836,153	888,174
	$	6,691,140	6,738,618	6,551,908	6,602,934

Temporarily Impaired Available for Sale Securities by Time Period Impaired

Following is a summary of temporarily impaired AFS securities by the time period impaired as of December 31, 2016 and December 26, 2015:

	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)
2016
Tax exempt bonds	$	2,360,143		24,416	6,099		233	2,366,242		24,649
Taxable bonds	1,921,367			33,354	51,769		549	1,973,136		33,903
Restricted investments	164,085			463	—		—	164,085		463
Equity securities	61,625			3,924	38,141		4,032	99,766		7,956
Total temporarily impaired AFS securities	$	4,507,220		62,157	96,009		4,814	4,603,229		66,971
2015
Tax exempt bonds	$	890,907		2,264	63,474		473	954,381		2,737
Taxable bonds	1,676,719			9,988	70,309		411	1,747,028		10,399
Restricted investments	163,159			1,389	—		—	163,159		1,389
Equity securities	274,517			20,561	16,112		5,796	290,629		26,357
Total temporarily impaired AFS securities	$	3,005,302		34,202	149,895		6,680	3,155,197		40,882