Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Cash flow from operating activities:
Net earnings	$ 489,001	$ 356,741	$ 342,391
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	389,393	352,796	293,169
Amortization of deferred policy acquisition costs	23,272	19,661	19,982
Interest credited to policy holders	20,465	18,110	22,890
Change in allowance for losses on trade receivables	(205)	(168)	(36)
Change in allowance for inventory reserves	(1,343)	(872)	871
Net gain on sale of real and personal property	(98,703)	(74,631)	(33,557)
Net gain (loss) on sale of investments	(4,491)	(3,925)	(6,411)
Deferred income taxes	138,075	76,500	46,371
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	14,765	9,632	62,506
Inventories	(9,009)	(1,579)	(11,495)
Prepaid expenses	(10,338)	(65,720)	2,186
Capitalization of deferred policy acquisition costs	(32,590)	(27,084)	(32,611)
Other assets	15,322	3,735	7,667
Related party assets	56,644	27,706	7,554
Accounts payable and accrued expenses	37,387	98,877	36,365
Policy benefits and losses, claims and loss expenses payable	9,626	(17,621)	(30,496)
Other policyholders' funds and liabilities	(349)	988	631
Deferred income	4,757	(13,181)	1,259
Related party liabilities	(616)	(866)	4,730
Net cash provided by operating activities	1,041,063	759,099	733,966
Cash flow from investing activities:
Property, plant and equipment	(1,509,154)	(1,041,931)	(1,000,243)
Short term investments	(515,899)	(290,379)	(270,690)
Fixed maturities investments	(417,062)	(214,371)	(282,424)
Equity securities	(1,315)	(3,759)	(1,562)
Preferred stock	(1,005)	(2,006)	(640)
Real estate	(75)	(15,399)	(532)
Mortgage loans	(102,588)	(42,683)	(52,419)
Proceeds from sale and paydowns of:
Property, plant and equipment	539,256	411,629	270,053
Short term investments	528,180	287,883	269,052
Fixed maturities investments	154,536	107,867	138,401
Equity securities	2,044	3,082	29,139
Preferred stock	$ 1,126	2,427	6,004
Real estate		396	544
Mortgage loans	$ 48,557	41,983	48,686
Net cash used by investing activities	(1,273,399)	(755,261)	(846,631)
Cash flow from financing activities:
Borrowings from credit facilities	855,972	657,535	431,029
Principal repayments on credit facilities	(428,403)	(593,722)	(293,068)
Debt issuance costs	(10,184)	(12,327)	(3,943)
Capital lease payments	(168,661)	(121,202)	(53,079)
Employee stock ownership plan	(9,302)	$ (7,939)	$ (207)
Securitization deposits	544
Common stock dividends paid	(78,374)	$ (19,594)	$ (19,568)
Investment contract deposits	298,237	105,019	117,723
Investment contract withdrawals	(52,957)	(54,108)	(34,677)
Net cash provided by financing activities	406,872	(46,338)	144,210
Effects of exchange rate on cash	(15,740)	(10,762)	(177)
Increase (decrease) in cash and cash equivalents	158,796	(53,262)	31,368
Cash and cash equivalents at the beginning of period	441,850	495,112	463,744
Cash and cash equivalents at the end of the period	$ 600,646	$ 441,850	$ 495,112