Significant Components of Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Deferred tax assets:
Net operating loss and credit carry forwards	$ 2,040	$ 2,007
Accrued expenses	150,935	153,807
Policy benefits and losses, claims and loss expenses payable, net	22,479	24,137
Unrealized losses	1,857
Other		454
Total deferred tax assets	177,311	180,405
Deferred tax liabilities:
Property, plant and equipment	593,654	552,548
Deferred policy acquisition costs	16,250	12,270
Unrealized gains		9,245
Other	3	0
Total deferred tax liabilities	609,907	574,063
Net deferred tax liability	$ 432,596	$ 393,658