Investments - Summary of Fixed Maturities and Equity Securities Available for Sale by Component (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 28, 2012
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	$ 12,488,875	$ 11,963,406
Total Available for Sale Securities Cost	12,489,750		11,978,281
Gross Unrealized Gains	802,229		1,667,520
Gross Unrealized Losses	(410,962)		(89,041)
Debt Securities Fair Value	12,879,133	13,541,193
Total Available for Sale Securities Fair Value	12,881,017	13,556,760	13,556,760
Total Available for Sale Amount per the Balance Sheet	12,881,017		13,556,760
Equity Securities Cost or Amortized Cost	875	14,875
Gross Unrealized Gains	1,009	692
Gross Unrealized Losses	0	0
Equity Securities Fair Value	1,884	15,567
Equity Securities Amount per the Balance Sheet	1,884	15,567
Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	12,488,875	11,963,406
Gross Unrealized Gains	801,220	1,666,828
Gross Unrealized Losses	(410,962)	(89,041)
Debt Securities Fair Value	12,879,133	13,541,193
Debt Securities Amount per the Balance Sheet	12,879,133	13,541,193
% of Total Fixed Maturities At Fair Value	100.00%	100.00%
U.S. Government Direct, Guaranteed, and Government-Sponsored Enterprises [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	428,106	492,928
Gross Unrealized Gains	362	1,948
Gross Unrealized Losses	(75,295)	(4,773)
Debt Securities Fair Value	353,173	490,103
Debt Securities Amount per the Balance Sheet	353,173	490,103
% of Total Fixed Maturities At Fair Value	3.00%	4.00%
States, Municipalities, and Political Subdivisions [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	1,278,434	1,283,883
Gross Unrealized Gains	69,817	173,649
Gross Unrealized Losses	(12,947)	(189)
Debt Securities Fair Value	1,335,304	1,457,343
Debt Securities Amount per the Balance Sheet	1,335,304	1,457,343
% of Total Fixed Maturities At Fair Value	10.00%	11.00%
Foreign Governments [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	43,811	33,577
Gross Unrealized Gains	411	988
Gross Unrealized Losses	(67)	0
Debt Securities Fair Value	44,155	34,565
Debt Securities Amount per the Balance Sheet	44,155	34,565
% of Total Fixed Maturities At Fair Value	0.00%	0.00%
Corporates [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	10,133,868	9,309,408
Gross Unrealized Gains	702,867	1,442,638
Gross Unrealized Losses	(300,389)	(55,023)
Debt Securities Fair Value	10,536,346	10,697,023
Debt Securities Amount per the Balance Sheet	10,536,346	10,697,023
% of Total Fixed Maturities At Fair Value	82.00%	79.00%
Collateralized Debt Obligations [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	66,173	64,622
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(7,968)	(18,051)
Debt Securities Fair Value	58,205	46,571
Debt Securities Amount per the Balance Sheet	58,205	46,571
% of Total Fixed Maturities At Fair Value	1.00%	0.00%
Other Asset-backed Securities [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	35,568	43,560
Gross Unrealized Gains	2,699	3,708
Gross Unrealized Losses	(98)	(401)
Debt Securities Fair Value	38,169	46,867
Debt Securities Amount per the Balance Sheet	38,169	46,867
% of Total Fixed Maturities At Fair Value	0.00%	0.00%
Redeemable Preferred Stocks [Member] | Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities Cost or Amortized Cost	502,915	735,428
Gross Unrealized Gains	25,064	43,897
Gross Unrealized Losses	(14,198)	(10,604)
Debt Securities Fair Value	513,781	768,721
Debt Securities Amount per the Balance Sheet	$ 513,781	$ 768,721
% of Total Fixed Maturities At Fair Value	4.00%	6.00%