Schedule Of Unrealized Investment Losses By Class Of Investment (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	$ 389,695
Fair Value, Twelve Months or Longer	1,020,658
Fair Value, Total	1,410,353
Unrealized Loss Less Than Twelve Months	(8,879)
Unrealized Loss Twelve Months or Longer	(149,027)
Unrealized Loss Total	(157,906)
U.S. Government Direct, Guaranteed, And Government-Sponsored Enterprises
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	5,236
Fair Value, Twelve Months or Longer	31
Fair Value, Total	5,267
Unrealized Loss Less Than Twelve Months	(8)
Unrealized Loss Twelve Months or Longer	(1)
Unrealized Loss Total	(9)
States, Municipalities, And Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	0
Fair Value, Twelve Months or Longer	17,550
Fair Value, Total	17,550
Unrealized Loss Less Than Twelve Months	0
Unrealized Loss Twelve Months or Longer	(415)
Unrealized Loss Total	(415)
Foreign Governments
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	0
Fair Value, Twelve Months or Longer	0
Fair Value, Total	0
Unrealized Loss Less Than Twelve Months	0
Unrealized Loss Twelve Months or Longer	0
Unrealized Loss Total	0
Corporates
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	245,694
Fair Value, Twelve Months or Longer	631,148
Fair Value, Total	876,842
Unrealized Loss Less Than Twelve Months	(7,047)
Unrealized Loss Twelve Months or Longer	(82,907)
Unrealized Loss Total	(89,954)
Collateralized Debt Obligations
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	0
Fair Value, Twelve Months or Longer	29,957
Fair Value, Total	29,957
Unrealized Loss Less Than Twelve Months	0
Unrealized Loss Twelve Months or Longer	(32,538)
Unrealized Loss Total	(32,538)
Other Asset-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	8,260
Fair Value, Twelve Months or Longer	7,152
Fair Value, Total	15,412
Unrealized Loss Less Than Twelve Months	(22)
Unrealized Loss Twelve Months or Longer	(1,253)
Unrealized Loss Total	(1,275)
Redeemable Preferred Stocks
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	130,419
Fair Value, Twelve Months or Longer	334,511
Fair Value, Total	464,930
Unrealized Loss Less Than Twelve Months	(1,789)
Unrealized Loss Twelve Months or Longer	(31,872)
Unrealized Loss Total	(33,661)
Total Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	389,609
Fair Value, Twelve Months or Longer	1,020,349
Fair Value, Total	1,409,958
Unrealized Loss Less Than Twelve Months	(8,866)
Unrealized Loss Twelve Months or Longer	(148,986)
Unrealized Loss Total	(157,852)
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than Twelve Months	86
Fair Value, Twelve Months or Longer	309
Fair Value, Total	395
Unrealized Loss Less Than Twelve Months	(13)
Unrealized Loss Twelve Months or Longer	(41)
Unrealized Loss Total	$ (54)