Consolidated Statement of Operations by Industry Segment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2013
Revenues:
Self-moving equipment rentals	$ 2,146,391		$ 1,955,423		$ 1,767,520
Self-storage revenues	211,136		181,794		152,660
Self-moving and self-storage products and service sales	244,177		234,187		221,117
Property management fees	25,341		24,493		24,378
Life insurance premiums	156,103		157,919		178,115
Property and casualty insurance premiums	46,456		41,052		34,342
Net investment and interest income	84,728		79,591		82,903
Other revenue	160,199		160,793		97,552
Total revenues	3,074,531		2,835,252		2,558,587
Costs and expenses:
Operating expenses	1,479,409		1,313,674		1,193,934
Commission expenses	249,642		227,332		204,758
Cost of sales	146,072		127,270		107,216
Benefits and losses	158,760		156,702		180,676
Amortization of deferred policy acquisition costs	19,661		19,982		17,376
Lease expense	79,798		100,466		117,448
Depreciation, net of (gains) losses on disposals	278,165		259,612		237,996
Total costs and expenses	2,411,507		2,205,038		2,059,404
Earnings from operations before equity in earnings of subsidiaries	663,024		630,214		499,183
Equity in earnings of subsidiaries	0		0		0
Earnings from operations	663,024		630,214		499,183
Interest expense	(97,525)		(92,692)		(90,696)
Fees and amortization on early extinguishment of debt	(4,081)		0		0
Total pretax earnings	561,418		537,522		408,487
Income tax expense	(204,677)		(195,131)		(143,779)
Earnings available to common shareholders	356,741		342,391		264,708
Operating Segments [Member] | Moving and Storage Consolidations [Member]
Revenues:
Self-moving equipment rentals	2,149,986		1,958,209		1,769,058
Self-storage revenues	211,136		181,794		152,660
Self-moving and self-storage products and service sales	244,177		234,187		221,117
Property management fees	25,341		24,493		24,378
Life insurance premiums	0		0		0
Property and casualty insurance premiums	0		0		0
Net investment and interest income	13,644		15,212		18,622
Other revenue	156,154		158,055		96,507
Total revenues	2,800,438		2,571,950		2,282,342
Costs and expenses:
Operating expenses	1,436,145		1,272,406		1,152,429
Commission expenses	249,642		227,332		204,758
Cost of sales	146,072		127,270		107,216
Benefits and losses	0		0		0
Amortization of deferred policy acquisition costs	0		0		0
Lease expense	79,984		100,649		117,615
Depreciation, net of (gains) losses on disposals	278,165		259,612		237,996
Total costs and expenses	2,190,008		1,987,269		1,820,014
Earnings from operations before equity in earnings of subsidiaries	610,430		584,681		462,328
Equity in earnings of subsidiaries	34,783		29,992		24,241
Earnings from operations	645,213		614,673		486,569
Interest expense	(98,163)		(93,162)		(90,990)
Fees and amortization on early extinguishment of debt	(4,801)
Total pretax earnings	542,969		521,511		395,579
Income tax expense	(186,228)		(179,120)		(130,871)
Earnings available to common shareholders	356,741		342,391		264,708
Operating Segments [Member] | Property and Casualty Insurance [Member]
Revenues:
Self-moving equipment rentals	0	[1]	0	[2]	0	[3]
Self-storage revenues	0	[1]	0	[2]	0	[3]
Self-moving and self-storage products and service sales	0	[1]	0	[2]	0	[3]
Property management fees	0	[1]	0	[2]	0	[3]
Life insurance premiums	0	[1]	0	[2]	0	[3]
Property and casualty insurance premiums	46,456	[1]	41,052	[2]	34,342	[3]
Net investment and interest income	12,819	[1]	10,592	[2]	13,858	[3]
Other revenue	0	[1]	0	[2]	0	[3]
Total revenues	59,275	[1]	51,644	[2]	48,200	[3]
Costs and expenses:
Operating expenses	24,802	[1]	20,799	[2]	18,007	[3]
Commission expenses	0	[1]	0	[2]	0	[3]
Cost of sales	0	[1]	0	[2]	0	[3]
Benefits and losses	10,996	[1]	11,513	[2]	15,999	[3]
Amortization of deferred policy acquisition costs	0	[1]	0	[2]	0	[3]
Lease expense	0	[1]	0	[2]	0	[3]
Depreciation, net of (gains) losses on disposals	0	[1]	0	[2]	0	[3]
Total costs and expenses	35,798	[1]	32,312	[2]	34,006	[3]
Earnings from operations before equity in earnings of subsidiaries	23,477	[1]	19,332	[2]	14,194	[3]
Equity in earnings of subsidiaries	0	[1]	0	[2]	0	[3]
Earnings from operations	23,477	[1]	19,332	[2]	14,194	[3]
Interest expense	0	[1]	0	[2]	0	[3]
Fees and amortization on early extinguishment of debt	0	[1]
Total pretax earnings	23,477	[1]	19,332	[2]	14,194	[3]
Income tax expense	(8,060)	[1]	(6,670)	[2]	(4,938)	[3]
Earnings available to common shareholders	15,417	[4]	12,662	[5]	9,256	[6]
Operating Segments [Member] | Life Insurance [Member]
Revenues:
Self-moving equipment rentals	0	[1]	0	[2]	0	[3]
Self-storage revenues	0	[1]	0	[2]	0	[3]
Self-moving and self-storage products and service sales	0	[1]	0	[2]	0	[3]
Property management fees	0	[1]	0	[2]	0	[3]
Life insurance premiums	156,103	[1]	157,919	[2]	178,115	[3]
Property and casualty insurance premiums	0	[1]	0	[2]	0	[3]
Net investment and interest income	59,051	[1]	54,398	[2]	50,850	[3]
Other revenue	4,502	[1]	3,211	[2]	2,525	[3]
Total revenues	219,656	[1]	215,528	[2]	231,490	[3]
Costs and expenses:
Operating expenses	22,476	[1]	23,686	[2]	26,482	[3]
Commission expenses	0	[1]	0	[2]	0	[3]
Cost of sales	0	[1]	0	[2]	0	[3]
Benefits and losses	147,764	[1]	145,189	[2]	164,677	[3]
Amortization of deferred policy acquisition costs	19,661	[1]	19,982	[2]	17,376	[3]
Lease expense	0	[1]	0	[2]	0	[3]
Depreciation, net of (gains) losses on disposals	0	[1]	0	[2]	0	[3]
Total costs and expenses	189,901	[1]	188,857	[2]	208,535	[3]
Earnings from operations before equity in earnings of subsidiaries	29,755	[1]	26,671	[2]	22,955	[3]
Equity in earnings of subsidiaries	0	[1]	0	[2]	0	[3]
Earnings from operations	29,755	[1]	26,671	[2]	22,955	[3]
Interest expense	0	[1]	0	[2]	0	[3]
Fees and amortization on early extinguishment of debt	0	[1]
Total pretax earnings	29,755	[1]	26,671	[2]	22,955	[3]
Income tax expense	(10,389)	[1]	(9,341)	[2]	(7,970)	[3]
Earnings available to common shareholders	19,366	[4]	17,330	[5]	14,985	[6]
Eliminations [Member]
Revenues:
Self-moving equipment rentals	(3,595)	[7]	(2,786)	[7]	(1,538)	[7]
Self-storage revenues	0		0		0
Self-moving and self-storage products and service sales	0		0		0
Property management fees	0		0		0
Life insurance premiums	0		0		0
Property and casualty insurance premiums	0		0		0
Net investment and interest income	(786)	[8]	(611)	[8]	(427)	[8]
Other revenue	(457)	[8]	(473)	[8]	(1,480)	[8]
Total revenues	(4,838)		(3,870)		(3,445)
Costs and expenses:
Operating expenses	(4,014)	[7],[8]	(3,217)	[7],[8]	(2,984)	[7],[8]
Commission expenses	0		0		0
Cost of sales	0		0		0
Benefits and losses	0		0		0
Amortization of deferred policy acquisition costs	0		0		0
Lease expense	(186)	[8]	(183)	[8]	(167)	[8]
Depreciation, net of (gains) losses on disposals	0		0		0
Total costs and expenses	(4,200)		(3,400)		(3,151)
Earnings from operations before equity in earnings of subsidiaries	(638)		(470)		(294)
Equity in earnings of subsidiaries	(34,783)	[9]	(29,992)	[9]	(24,241)	[9]
Earnings from operations	(35,421)		(30,462)		(24,535)
Interest expense	638	[8]	470	[8]	294	[8]
Fees and amortization on early extinguishment of debt	0
Total pretax earnings	(34,783)		(29,992)		(24,241)
Income tax expense	0		0		0
Earnings available to common shareholders	$ (34,783)		$ (29,992)		$ (24,241)

[1] Balances for the year ended December 31, 2014

[2] Balances for the year ended December 31, 2013

[3] Balances for the year ended December 31, 2012

[4] Balance for the period ended December 31, 2014

[5] Balance for the period ended December 31, 2013

[6] Balance for the period ended December 31, 2012

[7] Eliminate intercompany premiums

[8] Eliminate intercompany lease / interest income

[9] Eliminate equity in earnings of subsidiaries