Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flow from operating activities:
Net earnings	$ 398,424	$ 489,001	$ 356,741
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	481,520	389,393	352,796
Amortization of deferred policy acquisition costs	26,218	23,272	19,661
Amortization of debt issuance costs	4,062	3,419	3,786
Interest credited to policy holders	25,020	20,465	18,110
Change in allowance for losses on trade receivables	(46)	(205)	(168)
Change in allowance for inventory reserves	1,330	(1,343)	(872)
Net gain on sale of real and personal property	(36,085)	(98,703)	(74,631)
Net gain (loss) on sale of investments	(5,284)	(4,491)	(3,925)
Deferred income taxes	173,112	138,075	76,500
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	(2,890)	14,765	9,632
Inventories	(4,072)	(9,009)	(1,579)
Prepaid expenses	9,386	(10,338)	(65,720)
Capitalization of deferred policy acquisition costs	(27,111)	(32,590)	(27,084)
Other assets	(40,546)	11,903	(51)
Related party assets	343	56,644	27,706
Accounts payable and accrued expenses	(5,056)	37,312	98,877
Policy benefits and losses, claims and loss expenses payable	15,378	9,626	(17,621)
Other policyholders' funds and liabilities	1,499	(349)	988
Deferred income	5,921	4,757	(13,181)
Related party liabilities	(1,062)	(616)	(866)
Net cash provided by operating activities	1,020,061	1,040,988	759,099
Cash flow from investing activities:
Property, plant and equipment	(1,419,505)	(1,509,154)	(1,041,931)
Short term investments	(635,847)	(515,899)	(290,379)
Fixed maturities investments	(355,101)	(398,987)	(214,371)
Equity securities	(489)	(1,315)	(3,759)
Preferred stock		(1,005)	(2,006)
Real estate	(32,807)	(15,459)	(38,275)
Mortgage loans	(154,310)	(87,204)	(19,807)
Proceeds from sale and paydowns of:
Property, plant and equipment	487,475	539,256	411,629
Short term investments	655,726	528,180	287,883
Fixed maturities investments	190,578	154,536	107,867
Equity securities		2,044	3,082
Preferred stock	4,181	1,126	2,427
Real estate	8,753	21,589	28,485
Mortgage loans	106,832	26,968	13,894
Net cash used by investing activities	(1,144,514)	(1,255,324)	(755,261)
Cash flow from financing activities:
Borrowings from credit facilities	742,625	837,972	657,535
Principal repayments on credit facilities	(367,844)	(428,403)	(593,722)
Debt issuance costs	(5,055)	(10,184)	(12,327)
Capital lease payments	(212,545)	(168,661)	(121,202)
Employee stock ownership plan	(11,106)	(9,302)	(7,939)
Securitization deposits	446	544
Common stock dividends paid	(58,757)	(78,374)	(19,594)
Investment contract deposits	285,148	358,237	105,019
Investment contract withdrawals	(149,159)	(112,957)	(54,108)
Net cash provided by financing activities	223,753	388,872	(46,338)
Effects of exchange rate on cash	(2,140)	(15,740)	(10,762)
Increase (decrease) in cash and cash equivalents	97,160	158,796	(53,262)
Cash and cash equivalents at the beginning of period	600,646	441,850	495,112
Cash and cash equivalents at the end of the period	$ 697,806	$ 600,646	$ 441,850