Consolidating financial information by industry segment (Cash Flow Statements) (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2016		Jun. 30, 2015
Cash flow from operating activities:
Net earnings		$ 147,173		$ 171,285
Earnings from consolidated entities
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation		114,021		96,966
Amortization of deferred policy acquisition costs		7,942		4,778
Amortization of debt issuance costs		961		743
Interest credited to policy holders		5,059		5,484
Change in allowance for losses on trade receivables		21		(61)
Change in allowance for inventory reserves		1,221		(248)
Net gain on sale of real and personal property		(18,640)		(45,984)
Net (gain) loss on sale of investments		(2,406)		(1,453)
Deferred income tax		22,733		18,866
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables		(14,138)		(19,349)
Inventories		(4,391)		(140)
Prepaid expenses		39,828		56,624
Capitalization of deferred policy acquisition costs		(7,252)		(7,137)
Other assets		(3,392)		9,368
Related party assets		4,084		5,666
Accounts payable and accrued expenses		57,099		53,997
Policy benefits and losses, claims and loss expenses payable		1,373		11,669
Other policyholders' funds and liabilities		242		4,700
Deferred income		8,727		8,342
Related party liabilities		781		1,438
Net cash provided by operating activities		361,046		375,554
Cash flow from investing activities:
Property, plant and equipment		(437,287)		(452,572)
Short term investments		(277,038)		(73,517)
Fixed maturities investments		(166,648)		(47,072)
Equity securities				(967)
Preferred stock				(2)
Real estate		(3,495)		(23)
Mortgage loans		(62,572)		(82,839)
Proceeds from sale of:
Property, plant and equipment		147,196		194,133
Short term investments		279,341		88,332
Fixed maturities investments		55,946		30,340
Equity securities				799
Preferred stock		2,000
Real estate		831
Mortgage loans		94,015		14,306
Net cash used by investing activities		(367,711)		(329,082)
Cash flow from financing activities:
Borrowings from credit facilities		103,338		88,206
Principal repayments on credit facilities		(48,326)		(82,797)
Debt issuance costs		(223)
Capital lease payments		(37,405)		(33,974)
Employee Stock Ownership Plan		(1,393)		(1,388)
Securitization deposits		93
Common stock dividends paid		(19,586)
Investment contract deposits		74,157		33,768
Investment contract withdrawals		(14,051)		(13,215)
Net cash provided by (used in) financing activities		56,604		(9,400)
Effects of exchange rate on cash		(4,397)		(3,360)
Increase (decrease) in cash and cash equivalents		45,542		33,712
Cash and cash equivalents at the beginning of period		600,646		441,850
Cash and cash equivalents at the end of the period		646,188		475,562
Operating Segments [Member] | Moving and Storage Consolidations [Member]
Cash flow from operating activities:
Net earnings		147,173		171,285
Earnings from consolidated entities		(7,574)		(6,950)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation		114,021		96,966
Amortization of deferred policy acquisition costs
Amortization of debt issuance costs		961		743
Interest credited to policy holders
Change in allowance for losses on trade receivables		21		(61)
Change in allowance for inventory reserves		1,221		(248)
Net gain on sale of real and personal property		(18,640)		(45,984)
Net (gain) loss on sale of investments
Deferred income tax		22,401		19,675
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables		(10,746)		(17,122)
Inventories		(4,391)		(140)
Prepaid expenses		39,828		56,624
Capitalization of deferred policy acquisition costs
Other assets		(5,817)		8,494
Related party assets		3,687		5,496
Accounts payable and accrued expenses		58,699		52,642
Policy benefits and losses, claims and loss expenses payable		(1,600)		6,074
Other policyholders' funds and liabilities
Deferred income		8,727		8,342
Related party liabilities		861		830
Net cash provided by operating activities		348,832		356,666
Cash flow from investing activities:
Property, plant and equipment		(437,287)		(452,572)
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate		(3,495)
Mortgage loans		(1,838)		(8,226)
Proceeds from sale of:
Property, plant and equipment		147,196		194,133
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate
Mortgage loans		3,490		1,075
Net cash used by investing activities		(291,934)		(265,590)
Cash flow from financing activities:
Borrowings from credit facilities		103,338		41,206
Principal repayments on credit facilities		(48,326)		(65,797)
Debt issuance costs		(223)
Capital lease payments		(37,405)		(33,974)
Employee Stock Ownership Plan		(1,393)		(1,388)
Securitization deposits		93
Common stock dividends paid		(19,586)
Investment contract deposits
Investment contract withdrawals
Net cash provided by (used in) financing activities		(3,502)		(59,953)
Effects of exchange rate on cash		(4,397)		(3,360)
Increase (decrease) in cash and cash equivalents		48,999		27,763
Cash and cash equivalents at the beginning of period		585,666		431,873
Cash and cash equivalents at the end of the period		634,665		459,636
Operating Segments [Member] | Property and Casualty Insurance [Member]
Cash flow from operating activities:
Net earnings		4,877	[1]	4,211	[2]
Earnings from consolidated entities			[1]		[2]
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation			[1]		[2]
Amortization of deferred policy acquisition costs			[3]		[4]
Amortization of debt issuance costs			[1]		[2]
Interest credited to policy holders			[1]		[2]
Change in allowance for losses on trade receivables			[1]		[2]
Change in allowance for inventory reserves			[1]		[2]
Net gain on sale of real and personal property			[1]		[2]
Net (gain) loss on sale of investments		(2,163)	[1]	(781)	[2]
Deferred income tax		(21)	[1]	1,004	[2]
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables		(421)	[1]	(1,576)	[2]
Inventories			[1]		[2]
Prepaid expenses			[1]		[2]
Capitalization of deferred policy acquisition costs			[1]		[2]
Other assets		2,377	[1]	831	[2]
Related party assets		397	[1]	170	[2]
Accounts payable and accrued expenses		(142)	[1]	(232)	[2]
Policy benefits and losses, claims and loss expenses payable		(1,746)	[1]	(908)	[2]
Other policyholders' funds and liabilities		8	[1]	(193)	[2]
Deferred income			[1]		[2]
Related party liabilities		(7)	[1]	146	[2]
Net cash provided by operating activities		3,159	[1]	2,672	[2]
Cash flow from investing activities:
Property, plant and equipment			[1]		[2]
Short term investments		(18,901)	[1]	(11,824)	[2]
Fixed maturities investments		(13,469)	[1]	(9,827)	[2]
Equity securities	[2]
Preferred stock	[2]			(2)
Real estate			[1]	(6)	[2]
Mortgage loans		(3,063)	[1]		[2]
Proceeds from sale of:
Property, plant and equipment			[1]		[2]
Short term investments		11,246	[1]	10,298	[2]
Fixed maturities investments		8,201	[1]	6,221	[2]
Equity securities	[2]
Preferred stock	[1]	2,000
Real estate	[1]
Mortgage loans		6,217	[1]	4,064	[2]
Net cash used by investing activities		(7,769)	[1]	(1,076)	[2]
Cash flow from financing activities:
Borrowings from credit facilities			[1]		[2]
Principal repayments on credit facilities			[1]		[2]
Debt issuance costs	[1]
Capital lease payments			[1]		[2]
Employee Stock Ownership Plan			[1]		[2]
Securitization deposits	[1]
Common stock dividends paid	[1]
Investment contract deposits			[1]		[2]
Investment contract withdrawals			[1]		[2]
Net cash provided by (used in) financing activities			[1]		[2]
Effects of exchange rate on cash			[1]		[2]
Increase (decrease) in cash and cash equivalents		(4,610)	[1]	1,596	[2]
Cash and cash equivalents at the beginning of period		14,049	[5]	8,495
Cash and cash equivalents at the end of the period		9,439	[6]	10,091
Operating Segments [Member] | Life Insurance [Member]
Cash flow from operating activities:
Net earnings		2,697	[1]	2,739	[2]
Earnings from consolidated entities			[1]		[2]
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation			[1]		[2]
Amortization of deferred policy acquisition costs		7,942	[3]	4,778	[4]
Amortization of debt issuance costs			[1]		[2]
Interest credited to policy holders		5,059	[1]	5,484	[2]
Change in allowance for losses on trade receivables			[1]		[2]
Change in allowance for inventory reserves			[1]		[2]
Net gain on sale of real and personal property			[1]		[2]
Net (gain) loss on sale of investments		(243)	[1]	(672)	[2]
Deferred income tax		353	[1]	(1,813)	[2]
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables		(2,971)	[1]	(651)	[2]
Inventories			[1]		[2]
Prepaid expenses			[1]		[2]
Capitalization of deferred policy acquisition costs		(7,252)	[1]	(7,137)	[2]
Other assets		48	[1]	43	[2]
Related party assets			[1]		[2]
Accounts payable and accrued expenses		(1,458)	[1]	1,587	[2]
Policy benefits and losses, claims and loss expenses payable		4,719	[1]	6,503	[2]
Other policyholders' funds and liabilities		234	[1]	4,893	[2]
Deferred income			[1]		[2]
Related party liabilities		(73)	[1]	462	[2]
Net cash provided by operating activities		9,055	[1]	16,216	[2]
Cash flow from investing activities:
Property, plant and equipment			[1]		[2]
Short term investments		(258,137)	[1]	(61,693)	[2]
Fixed maturities investments		(153,179)	[1]	(37,245)	[2]
Equity securities	[2]			(967)
Preferred stock	[2]
Real estate			[1]	(17)	[2]
Mortgage loans		(57,671)	[1]	(74,613)	[2]
Proceeds from sale of:
Property, plant and equipment			[1]		[2]
Short term investments		268,095	[1]	78,034	[2]
Fixed maturities investments		47,745	[1]	24,119	[2]
Equity securities	[2]			799
Preferred stock	[1]
Real estate	[1]	831
Mortgage loans		84,308	[1]	9,167	[2]
Net cash used by investing activities		(68,008)	[1]	(62,416)	[2]
Cash flow from financing activities:
Borrowings from credit facilities			[1]	47,000	[2]
Principal repayments on credit facilities			[1]	(17,000)	[2]
Debt issuance costs	[1]
Capital lease payments			[1]		[2]
Employee Stock Ownership Plan			[1]		[2]
Securitization deposits	[1]
Common stock dividends paid	[1]
Investment contract deposits		74,157	[1]	33,768	[2]
Investment contract withdrawals		(14,051)	[1]	(13,215)	[2]
Net cash provided by (used in) financing activities		60,106	[1]	50,553	[2]
Effects of exchange rate on cash			[1]		[2]
Increase (decrease) in cash and cash equivalents		1,153	[1]	4,353	[2]
Cash and cash equivalents at the beginning of period		931	[5]	1,482
Cash and cash equivalents at the end of the period		2,084	[6]	5,835
Consolidation, Eliminations [Member]
Cash flow from operating activities:
Net earnings		(7,574)		(6,950)
Earnings from consolidated entities		7,574		6,950
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation
Amortization of deferred policy acquisition costs
Amortization of debt issuance costs
Interest credited to policy holders
Change in allowance for losses on trade receivables
Change in allowance for inventory reserves
Net gain on sale of real and personal property
Net (gain) loss on sale of investments
Deferred income tax
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables
Inventories
Prepaid expenses
Capitalization of deferred policy acquisition costs
Other assets
Related party assets
Accounts payable and accrued expenses
Policy benefits and losses, claims and loss expenses payable
Other policyholders' funds and liabilities
Deferred income
Related party liabilities
Net cash provided by operating activities
Cash flow from investing activities:
Property, plant and equipment
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate
Mortgage loans
Proceeds from sale of:
Property, plant and equipment
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate
Mortgage loans
Net cash used by investing activities
Cash flow from financing activities:
Borrowings from credit facilities
Principal repayments on credit facilities
Debt issuance costs
Capital lease payments
Employee Stock Ownership Plan
Securitization deposits
Common stock dividends paid
Investment contract deposits
Investment contract withdrawals
Net cash provided by (used in) financing activities
Effects of exchange rate on cash
Increase (decrease) in cash and cash equivalents
Cash and cash equivalents at the beginning of period
Cash and cash equivalents at the end of the period

[1] Balance for the period ended March 31, 2016

[2] Balance for the period ended March 31, 2015

[3] Balances for the quarter ended March 31, 2016

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

[5] Balances as of December 31, 2015

[6] Balances as of March 31, 2016