Consolidating financial information by industry segment (Statements of Operations) (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Revenues:
Self-moving equipment rentals		$ 698,219		$ 653,534		$ 1,327,505		$ 1,229,009
Self-storage revenues		62,060		52,986		119,251		102,120
Self-moving and self-storage products and service sales		70,703		68,043		147,961		142,522
Property management fees		6,320		5,796		12,431		11,473
Life insurance premiums		40,515		39,041		80,781		76,971
Property and casualty insurance premiums		13,372		12,463		23,928		22,081
Net investment and interest income		22,151		21,856		44,123		42,902
Other revenue		49,563		52,772		91,728		98,368
Total revenues		962,903		906,491		1,847,708		1,725,446
Costs and expenses:
Operating expenses		406,282		383,970		769,451		747,269
Commission expenses		80,799		76,160		153,857		142,500
Cost of sales		39,881		39,836		81,136		81,464
Benefits and losses		43,428		39,558		86,819		80,342
Amortization of deferred policy acquisition costs		5,643		4,290		10,421		8,474
Lease expense		12,724		19,775		29,788		42,245
Depreciation, net of (gains) losses on disposals		63,078		67,066		114,060		128,117
Total costs and expenses		651,835		630,655		1,245,532		1,230,411
Earnings (loss) from operations before equity in earnings of subsidiaries		311,068		$ 275,836		602,176		495,035
Equity in earnings of subsidiaries
Earnings from operations		311,068		$ 275,836		602,176		495,035
Interest expense		$ (23,973)		(24,877)		$ (46,073)		(49,025)
Fees and amortization on early extinguishment of debt				(4,081)				(4,081)
Pretax earnings		$ 287,095		246,878		$ 556,103		441,929
Income tax expense		(103,716)		(90,631)		(201,439)		(161,208)
Earnings available to common shareholders		183,379		156,247		354,664		280,721
Operating Segments [Member] | Moving and Storage Consolidations [Member]
Revenues:
Self-moving equipment rentals		699,184		654,528		1,329,223		1,230,695
Self-storage revenues		62,060		52,986		119,251		102,120
Self-moving and self-storage products and service sales		70,703		68,043		147,961		142,522
Property management fees		$ 6,320		$ 5,796		$ 12,431		$ 11,473
Life insurance premiums
Property and casualty insurance premiums
Net investment and interest income		$ 1,845		$ 3,470		$ 4,662		$ 7,947
Other revenue		48,182		51,322		89,606		96,309
Total revenues		888,294		836,145		1,703,134		1,591,066
Costs and expenses:
Operating expenses		394,660		372,766		746,515		725,397
Commission expenses		80,799		76,160		153,857		142,500
Cost of sales		$ 39,881		$ 39,836		$ 81,136		$ 81,464
Benefits and losses
Amortization of deferred policy acquisition costs
Lease expense		$ 12,770		$ 19,821		$ 29,881		$ 42,335
Depreciation, net of (gains) losses on disposals		63,078		67,066		114,060		128,117
Total costs and expenses		591,188		575,649		1,125,449		1,119,813
Earnings (loss) from operations before equity in earnings of subsidiaries		297,106		260,496		577,685		471,253
Equity in earnings of subsidiaries		9,179		10,081		16,129		15,675
Earnings from operations		306,285		270,577		593,814		486,928
Interest expense		(24,133)		(25,040)		(46,393)		(49,343)
Fees and amortization on early extinguishment of debt				(4,081)				(4,081)
Pretax earnings		282,152		241,456		547,421		433,504
Income tax expense		(98,773)		(85,209)		(192,757)		(152,783)
Earnings available to common shareholders		$ 183,379		$ 156,247		$ 354,664		$ 280,721
Operating Segments [Member] | Property and Casualty Insurance [Member]
Revenues:
Self-moving equipment rentals			[1]		[2]		[3]		[4]
Self-storage revenues			[1]		[2]		[3]		[4]
Self-moving and self-storage products and service sales			[1]		[2]		[3]		[4]
Property management fees			[1]		[2]		[3]		[4]
Life insurance premiums			[1]		[2]		[3]		[4]
Property and casualty insurance premiums		$ 13,372	[1]	$ 12,463	[2]	$ 23,928	[3]	$ 22,081	[4]
Net investment and interest income		$ 3,253	[1]	$ 4,068	[2]	$ 7,587	[3]	$ 6,862	[4]
Other revenue			[1]		[2]		[3]		[4]
Total revenues		$ 16,625	[1]	$ 16,531	[2]	$ 31,515	[3]	$ 28,943	[4]
Costs and expenses:
Operating expenses		$ 7,089	[1]	$ 6,711	[2]	$ 13,428	[3]	$ 12,512	[4]
Commission expenses			[1]		[2]		[3]		[4]
Cost of sales			[1]		[2]		[3]		[4]
Benefits and losses		$ 3,471	[1]	$ 2,848	[2]	$ 5,544	[3]	$ 5,437	[4]
Amortization of deferred policy acquisition costs			[1]		[2]		[3]		[4]
Lease expense			[1]		[2]		[3]		[4]
Depreciation, net of (gains) losses on disposals			[1]		[2]		[3]		[4]
Total costs and expenses		$ 10,560	[1]	$ 9,559	[2]	$ 18,972	[3]	$ 17,949	[4]
Earnings (loss) from operations before equity in earnings of subsidiaries		$ 6,065	[1]	$ 6,972	[2]	$ 12,543	[3]	$ 10,994	[4]
Equity in earnings of subsidiaries			[1]		[2]		[3]		[4]
Earnings from operations		$ 6,065	[1]	$ 6,972	[2]	$ 12,543	[3]	$ 10,994	[4]
Interest expense			[1]		[2]		[3]		[4]
Fees and amortization on early extinguishment of debt					[2]				[4]
Pretax earnings		$ 6,065	[1]	$ 6,972	[2]	$ 12,543	[3]	$ 10,994	[4]
Income tax expense		(2,123)	[1]	(2,441)	[2]	(4,390)	[3]	(3,849)	[4]
Earnings available to common shareholders		$ 3,942	[1]	$ 4,531	[2]	$ 8,153	[5]	$ 7,145	[6]
Operating Segments [Member] | Life Insurance [Member]
Revenues:
Self-moving equipment rentals			[1]		[2]		[3]		[4]
Self-storage revenues			[1]		[2]		[3]		[4]
Self-moving and self-storage products and service sales			[1]		[2]		[3]		[4]
Property management fees			[1]		[2]		[3]		[4]
Life insurance premiums		$ 40,515	[1]	$ 39,041	[2]	$ 80,781	[3]	$ 76,971	[4]
Property and casualty insurance premiums			[1]		[2]		[3]		[4]
Net investment and interest income		$ 17,248	[1]	$ 14,518	[2]	$ 32,268	[3]	$ 28,483	[4]
Other revenue		1,424	[1]	1,564	[2]	2,207	[3]	2,289	[4]
Total revenues		59,187	[1]	55,123	[2]	115,256	[3]	107,743	[4]
Costs and expenses:
Operating expenses		$ 5,530	[1]	$ 5,592	[2]	$ 11,292	[3]	$ 11,258	[4]
Commission expenses			[1]		[2]		[3]		[4]
Cost of sales			[1]		[2]		[3]		[4]
Benefits and losses		$ 39,957	[1]	$ 36,710	[2]	$ 81,275	[3]	$ 74,905	[4]
Amortization of deferred policy acquisition costs		$ 5,643	[1]	$ 4,290	[2]	$ 10,421	[3]	$ 8,474	[4]
Lease expense			[1]		[2]		[3]		[4]
Depreciation, net of (gains) losses on disposals			[1]		[2]		[3]		[4]
Total costs and expenses		$ 51,130	[1]	$ 46,592	[2]	$ 102,988	[3]	$ 94,637	[4]
Earnings (loss) from operations before equity in earnings of subsidiaries		$ 8,057	[1]	$ 8,531	[2]	$ 12,268	[3]	$ 13,106	[4]
Equity in earnings of subsidiaries			[1]		[2]		[3]		[4]
Earnings from operations		$ 8,057	[1]	$ 8,531	[2]	$ 12,268	[3]	$ 13,106	[4]
Interest expense			[1]		[2]		[3]		[4]
Fees and amortization on early extinguishment of debt					[2]				[4]
Pretax earnings		$ 8,057	[1]	$ 8,531	[2]	$ 12,268	[3]	$ 13,106	[4]
Income tax expense		(2,820)	[1]	(2,981)	[2]	(4,292)	[3]	(4,576)	[4]
Earnings available to common shareholders		5,237	[1]	5,550	[2]	7,976	[5]	8,530	[6]
Consolidation, Eliminations [Member]
Revenues:
Self-moving equipment rentals		$ (965)	[7]	$ (994)	[7]	$ (1,718)	[8]	$ (1,686)	[7]
Self-storage revenues
Self-moving and self-storage products and service sales
Property management fees
Life insurance premiums
Property and casualty insurance premiums
Net investment and interest income	[9]	$ (195)		$ (200)		$ (394)		$ (390)
Other revenue	[9]	(43)		(114)		(85)		(230)
Total revenues		(1,203)		(1,308)		(2,197)		(2,306)
Costs and expenses:
Operating expenses	[9]	$ (997)	[7]	$ (1,099)	[7]	$ (1,784)	[8]	$ (1,898)	[7]
Commission expenses
Cost of sales
Benefits and losses
Amortization of deferred policy acquisition costs
Lease expense	[9]	$ (46)		$ (46)		$ (93)		$ (90)
Depreciation, net of (gains) losses on disposals
Total costs and expenses		$ (1,043)		$ (1,145)		$ (1,877)		$ (1,988)
Earnings (loss) from operations before equity in earnings of subsidiaries		(160)		(163)		(320)		(318)
Equity in earnings of subsidiaries	[10]	(9,179)		(10,081)		(16,129)		(15,675)
Earnings from operations		(9,339)		(10,244)		(16,449)		(15,993)
Interest expense	[9]	160		$ 163		320		$ 318
Fees and amortization on early extinguishment of debt
Pretax earnings		$ (9,179)		$ (10,081)		$ (16,129)		$ (15,675)
Income tax expense
Earnings available to common shareholders		$ (9,179)		$ (10,081)		$ (16,129)		$ (15,675)

[1] Balances for the quarter ended June 30, 2015

[2] Balances for the quarter ended June 30, 2014

[3] Balances for the six months ended June 30, 2015

[4] Balances for the six months ended June 30, 2014

[5] Balance for the period ended June 30, 2015

[6] Balance for the period ended June 30, 2014

[7] Eliminate intercompany premiums

[8] Eliminate intercompany premiums

[9] Eliminate intercompany lease / interest income

[10] Eliminate equity in earnings of subsidiaries