Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Cash flow from operating activities:
Net earnings	$ 790,583	$ 398,424	$ 489,001
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation	555,069	481,520	389,393
Amortization of deferred policy acquisition costs	24,514	26,218	23,272
Amortization of debt issuance costs	3,868	4,062	3,419
Interest credited to policyholders	32,302	25,020	20,465
Change in allowance for losses on trade receivables	(120)	(46)	(205)
Change in allowance for inventory reserves	5,065	1,330	(1,343)
Net gains on disposal of personal property	(11,822)	(32,495)	(98,158)
Net gains on disposal of real estate	(195,414)	(3,590)	(545)
Net gains on sales of investments	(6,269)	(5,284)	(4,491)
Deferred income taxes	(193,434)	173,112	138,075
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables	(15,329)	(2,890)	14,765
Inventories and parts	(12,384)	(4,072)	(9,009)
Prepaid expenses	(40,765)	9,386	(10,338)
Capitalization of deferred policy acquisition costs	(27,350)	(27,111)	(32,590)
Other assets	(165,968)	(2,488)	16,261
Related party assets	53,408	343	56,644
Accounts payable and accrued expenses	(25,546)	(5,056)	37,312
Policy benefits and losses, claims and loss expenses payable	161,121	15,378	9,626
Other policyholders' funds and liabilities	(109)	1,499	(349)
Deferred income	5,524	5,921	4,757
Related party liabilities	(616)	(1,062)	(616)
Net cash provided by operating activities	936,328	1,058,119	1,045,346
Cash flow from investing activities:
Escrow deposits	31,362	(38,058)	(4,358)
Purchase of:
Property, plant and equipment	(1,363,745)	(1,419,505)	(1,509,154)
Short term investments	(63,556)	(635,847)	(515,899)
Fixed maturities investments	(390,900)	(355,101)	(398,987)
Equity securities	(662)	(489)	(1,315)
Preferred stock	(1,000)		(1,005)
Real estate	(1,939)	(32,807)	(15,459)
Mortgage loans	(83,507)	(154,310)	(87,204)
Proceeds from sale and paydowns of:
Property, plant and equipment	699,803	487,475	539,256
Short term investments	67,790	655,726	528,180
Fixed maturities investments	164,825	190,578	154,536
Equity securities			2,044
Preferred stock	4,208	4,181	1,126
Real estate	2,783	8,753	21,589
Mortgage loans	37,590	106,832	26,968
Net cash used by investing activities	(896,948)	(1,182,572)	(1,259,682)
Cash flow from financing activities:
Borrowings from credit facilities	498,464	742,625	837,972
Principal repayments on credit facilities	(356,451)	(367,844)	(428,403)
Debt issuance costs	(5,111)	(5,055)	(10,184)
Capital lease payments	(296,363)	(212,545)	(168,661)
Employee stock ownership plan	(11,640)	(11,106)	(9,302)
Securitization deposits	(2,180)	446	544
Common stock dividends paid	(29,380)	(58,757)	(78,374)
Investment contract deposits	401,814	285,148	358,237
Investment contract withdrawals	(182,549)	(149,159)	(112,957)
Net cash provided by financing activities	16,604	223,753	388,872
Effects of exchange rate on cash	5,598	(2,140)	(15,740)
Increase (decrease) in cash and cash equivalents	61,582	97,160	158,796
Cash and cash equivalents at the beginning of period	697,806	600,646	441,850
Cash and cash equivalents at the end of the period	$ 759,388	$ 697,806	$ 600,646