Consolidating financial information by industry segment (Statements of Operations) (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2015		Jun. 30, 2014
Revenues:
Self-moving equipment rentals		$ 629,286		$ 575,475
Self-storage revenues		57,191		49,134
Self-moving and self-storage products and service sales		77,258		74,479
Property management fees		6,111		5,677
Life insurance premiums		40,266		37,930
Property and casualty insurance premiums		10,556		9,618
Net investment and interest income		21,972		21,046
Other revenue		42,165		45,596
Total revenues		884,805		818,955
Costs and expenses:
Operating expenses		363,169		363,299
Commission expenses		73,058		66,340
Cost of sales		41,255		41,628
Benefits and losses		43,391		40,784
Amortization of deferred policy acquisition costs		4,778		4,184
Lease expense		17,064		22,470
Depreciation, net of (gains) losses on disposals		50,982		61,051
Total costs and expenses		593,697		599,756
Earnings (loss) from operations before equity in earnings of subsidiaries		291,008		$ 219,199
Equity in earnings of subsidiaries
Earnings from operations		291,108		$ 219,199
Interest expense		(22,100)		(24,148)
Pretax earnings		269,008		195,051
Income tax expense		(97,723)		(70,577)
Earnings available to common shareholders		171,285		124,474
Operating Segments [Member] | Moving and Storage Consolidations [Member]
Revenues:
Self-moving equipment rentals		630,039		576,167
Self-storage revenues		57,191		49,134
Self-moving and self-storage products and service sales		77,258		74,479
Property management fees		$ 6,111		$ 5,677
Life insurance premiums
Property and casualty insurance premiums
Net investment and interest income		$ 2,817		$ 4,477
Other revenue		41,424		44,987
Total revenues		814,840		754,921
Costs and expenses:
Operating expenses		351,855		352,631
Commission expenses		73,058		66,340
Cost of sales		$ 41,255		$ 41,628
Benefits and losses
Amortization of deferred policy acquisition costs
Lease expense		$ 17,111		$ 22,514
Depreciation, net of (gains) losses on disposals		50,982		61,051
Total costs and expenses		534,261		544,164
Earnings (loss) from operations before equity in earnings of subsidiaries		280,579		210,757
Equity in earnings of subsidiaries		6,950		5,594
Earnings from operations		287,529		216,351
Interest expense		(22,260)		(24,303)
Pretax earnings		265,269		192,048
Income tax expense		(93,984)		(67,574)
Earnings available to common shareholders		$ 171,285		$ 124,474
Operating Segments [Member] | Property and Casualty Insurance [Member]
Revenues:
Self-moving equipment rentals
Self-storage revenues
Self-moving and self-storage products and service sales
Property management fees
Life insurance premiums
Property and casualty insurance premiums		$ 10,556	[1]	$ 9,618	[2]
Net investment and interest income		$ 4,334	[1]	$ 2,794	[2]
Other revenue
Total revenues		$ 14,890	[1]	$ 12,412	[2]
Costs and expenses:
Operating expenses		$ 6,339	[1]	$ 5,801	[2]
Commission expenses
Cost of sales
Benefits and losses		$ 2,073	[1]	$ 2,589	[2]
Amortization of deferred policy acquisition costs
Lease expense
Depreciation, net of (gains) losses on disposals
Total costs and expenses		$ 8,412	[1]	$ 8,390	[2]
Earnings (loss) from operations before equity in earnings of subsidiaries		$ 6,478	[1]	$ 4,022	[2]
Equity in earnings of subsidiaries
Earnings from operations		$ 6,478	[1]	$ 4,022	[2]
Interest expense
Pretax earnings		$ 6,478	[1]	$ 4,022	[2]
Income tax expense		(2,267)	[1]	(1,408)	[2]
Earnings available to common shareholders		$ 4,211	[1]	$ 2,614	[2]
Operating Segments [Member] | Life Insurance [Member]
Revenues:
Self-moving equipment rentals
Self-storage revenues
Self-moving and self-storage products and service sales
Property management fees
Life insurance premiums		$ 40,266	[1]	$ 37,930	[2]
Property and casualty insurance premiums
Net investment and interest income		$ 15,020	[1]	$ 13,965	[2]
Other revenue		783	[1]	725	[2]
Total revenues		56,069	[1]	52,620	[2]
Costs and expenses:
Operating expenses		$ 5,762	[1]	$ 5,666	[2]
Commission expenses
Cost of sales
Benefits and losses		$ 41,318	[1]	$ 38,195	[2]
Amortization of deferred policy acquisition costs		$ 4,778	[1]	$ 4,184	[2]
Lease expense
Depreciation, net of (gains) losses on disposals
Total costs and expenses		$ 51,858	[1]	$ 48,045	[2]
Earnings (loss) from operations before equity in earnings of subsidiaries		$ 4,211	[1]	$ 4,575	[2]
Equity in earnings of subsidiaries
Earnings from operations		$ 4,211	[1]	$ 4,575	[2]
Interest expense
Pretax earnings		$ 4,211	[1]	$ 4,575	[2]
Income tax expense		(1,472)	[1]	(1,595)	[2]
Earnings available to common shareholders		2,739	[1]	2,980	[2]
Consolidation, Eliminations [Member]
Revenues:
Self-moving equipment rentals	[3]	$ (753)		$ (692)
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	[4]	$ (199)		$ (190)
Other revenue	[4]	(42)		(116)
Total revenues		(994)		(998)
Costs and expenses:
Operating expenses	[3],[4]	$ (787)		$ (799)
Commission expenses
Cost of sales
Benefits and losses
Amortization of deferred policy acquisition costs
Lease expense	[4]	$ (47)		$ (44)
Depreciation, net of (gains) losses on disposals
Total costs and expenses		$ (834)		$ (843)
Earnings (loss) from operations before equity in earnings of subsidiaries		(160)		(155)
Equity in earnings of subsidiaries	[5]	(6,950)		(5,594)
Earnings from operations		(7,110)		(5,749)
Interest expense	[4]	160		155
Pretax earnings		$ (6,950)		$ (5,594)
Income tax expense
Earnings available to common shareholders		$ (6,950)		$ (5,594)

[1] Balances for the quarter ended March 31, 2015

[2] Balances for the quarter ended March 31, 2014

[3] Eliminate intercompany premiums

[4] Eliminate intercompany lease / interest income

[5] Eliminate equity in earnings of subsidiaries