Acquisitions - Components of Net Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Business Acquisition [Line Items]
DAC	$ 9,906	$ 74,175
Investments	438,655	246,632
Other deferred tax liabilities	7,936	5,705
Net current and noncurrent deferred tax liabilities	(69,687)	(101,436)
FGL [Member]
Business Acquisition [Line Items]
DAC	96,764
Insurance reserves and claim related adjustments	401,659
Net operating losses	128,437
Capital losses (carryovers and deferred)	267,468
Tax credits	75,253
Other deferred tax assets	24,066
Total deferred tax assets	993,647
Valuation allowance	(405,370)
Deferred tax assets, net of valuation allowance	588,277
VOBA	202,007
Investments	121,160
Other deferred tax liabilities	12,438
Total deferred tax liabilities	335,605
Net current and noncurrent deferred tax liabilities	$ 252,672