Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Cash flow from operating activities:
Net earnings	$ 356,741	$ 342,391	$ 264,708
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	352,796	293,169	260,492
Amortization of deferred policy acquisition costs	19,661	19,982	17,376
Change in allowance for losses on trade receivables	(168)	(36)	(134)
Change in allowance for inventory reserves	(872)	871	1,133
Net gain on sale of real and personal property	(74,631)	(33,557)	(22,496)
Net (gain) loss on sale of investments	(3,925)	(6,411)	(8,323)
Deferred income taxes	76,500	46,371	13,518
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	9,632	62,506	36,322
Inventories	(1,579)	(11,495)	1,206
Prepaid expenses	(65,720)	2,186	(15,587)
Capitalization of deferred policy acquisition costs	(27,084)	(32,611)	(50,640)
Other assets	3,735	7,667	21,556
Related party assets	27,706	7,554	133,672
Accounts payable and accrued expenses	166,056	34,731	40,032
Policy benefits and losses, claims and loss expenses payable	(17,621)	(30,496)	(30,478)
Other policyholders' funds and liabilities	1,010	693	21
Deferred income	(13,181)	1,259	(1,312)
Related party liabilities	(866)	4,730	464
Net cash provided by operating activities	808,190	709,504	661,530
Cash flow from investing activities:
Property, plant and equipment	(1,111,899)	(999,365)	(655,984)
Short term investments	(290,379)	(270,690)	(411,638)
Fixed maturities investments	(214,371)	(282,424)	(443,262)
Equity securities	(3,759)	(1,562)	(16,289)
Preferred stock	(2,006)	(640)	(6,296)
Real estate	(15,399)	(532)	(1,073)
Mortgage loans	(42,683)	(52,419)	(80,711)
Proceeds from sale and paydowns of:
Property, plant and equipment	411,629	270,053	220,699
Short term investments	287,883	269,052	417,520
Fixed maturities investments	107,867	138,401	160,806
Equity securities	3,082	29,139	372
Preferred stock	2,427	6,004	7,258
Real estate	396	544	671
Mortgage loans	41,983	48,686	95,714
Net cash used by investing activities	(825,229)	(845,753)	(712,213)
Cash flow from financing activities:
Borrowings from credit facilities	657,535	431,029	270,546
Principal repayments on credit facilities	(593,722)	(293,068)	(257,957)
Debt issuance costs	(12,327)	(3,943)	(2,223)
Capital lease payments	(121,202)	(53,079)	(26,877)
Leveraged Employee Stock Ownership Plan	(5,172)	487	692
Securitization deposits	0	0	1,195
Common stock dividends paid	(19,594)	(19,568)	(97,421)
Investment contract deposits	123,129	140,613	301,729
Investment contract withdrawals	(54,108)	(34,677)	(31,901)
Net cash provided by financing activities	(25,461)	167,794	157,783
Effects of exchange rate on cash	(10,762)	(177)	(536)
Increase (decrease) in cash and cash equivalents	(53,262)	31,368	106,564
Cash and cash equivalents at the beginning of period	495,112	463,744	357,180
Cash and cash equivalents at the end of the period	$ 441,850	$ 495,112	$ 463,744