Consolidating financial information by industry segment (Cash Flow Statements) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2015		Dec. 31, 2014
Cash flow from operating activities:
Net earnings		$ 81,769		$ 66,540		$ 436,433		$ 347,261
Earnings from consolidated entities
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation						$ 287,562		$ 259,871
Amortization of deferred policy acquisition costs		5,138		4,722		15,559		13,196
Change in allowance for losses on trade receivables						(182)		(212)
Change in allowance for inventory reserves						(1,939)		(744)
Net gain on sale of real and personal property		(8,984)		(5,444)		(87,789)		(49,944)
Net (gain) loss on sale of investments						(3,779)		(3,254)
Deferred income tax						151,399		71,485
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables						8,568		1,895
Inventories						(3,887)		(2,053)
Prepaid expenses						(57,015)		(38,905)
Capitalization of deferred policy acquisition costs						(24,803)		(20,158)
Other assets						20,680		(41,663)
Related party assets						49,803		20,770
Accounts payable and accrued expenses						37,323		(3,806)
Policy benefits and losses, claims and loss expenses payable						12,976		(17,587)
Other policyholders' funds and liabilities						(560)		2,730
Deferred income						1,005		(16,732)
Related party liabilities						(878)		22
Net cash provided by operating activities						840,476		522,172
Cash flow from investing activities:
Property, plant and equipment						(1,051,830)		(725,447)
Short term investments						(391,683)		(203,018)
Fixed maturities investments						(318,664)		(181,824)
Equity securities						(1,315)		(3,759)
Preferred stock						(5)		(5)
Real estate						(23)		(11,328)
Mortgage loans						(99,549)		(37,365)
Proceeds from sale of:
Property, plant and equipment						463,602		321,680
Short term investments						400,844		220,610
Fixed maturities investments						135,727		75,372
Equity securities						$ 808		3,082
Preferred stock								2,027
Real estate								396
Mortgage loans						$ 34,141		33,192
Net cash used by investing activities						(827,947)		(506,387)
Cash flow from financing activities:
Borrowings from credit facilities						508,276		510,074
Principal repayments on credit facilities						(280,304)		(266,672)
Debt issuance costs						(5,957)		(9,697)
Capital lease payments						(110,202)		(65,478)
Employee Stock Ownership Plan						(1,559)		$ (184)
Securitization deposits						448
Common stock dividends paid						(78,374)
Investment contract deposits						246,756		$ 94,979
Investment contract withdrawals						(41,258)		(38,653)
Net cash provided by (used in) financing activities						237,826		224,369
Effects of exchange rate on cash						(17,578)		(6,243)
Increase (decrease) in cash and cash equivalents						232,777		233,911
Cash and cash equivalents at the beginning of period						441,850		495,112
Cash and cash equivalents at the end of the period		674,627		729,023		674,627		729,023
Operating Segments [Member] | Moving and Storage Consolidations [Member]
Cash flow from operating activities:
Net earnings		$ 81,769		$ 66,540		436,433		347,261
Earnings from consolidated entities						(25,219)		(25,763)
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation						$ 287,562		$ 259,871
Amortization of deferred policy acquisition costs
Change in allowance for losses on trade receivables						$ 29		$ (201)
Change in allowance for inventory reserves						(1,939)		(744)
Net gain on sale of real and personal property						$ (87,789)		$ (49,944)
Net (gain) loss on sale of investments
Deferred income tax						$ 145,104		$ 64,058
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables						(5,420)		(9,126)
Inventories						(3,887)		(2,053)
Prepaid expenses						$ (57,015)		$ (38,905)
Capitalization of deferred policy acquisition costs
Other assets						$ 19,226		$ (41,905)
Related party assets						49,512		21,474
Accounts payable and accrued expenses						16,703		(13,095)
Policy benefits and losses, claims and loss expenses payable						$ 20,712		$ (4,623)
Other policyholders' funds and liabilities
Deferred income						$ 1,005		$ (16,732)
Related party liabilities						(752)		(235)
Net cash provided by operating activities						794,265		489,338
Cash flow from investing activities:
Property, plant and equipment						$ (1,051,830)		$ (725,447)
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate
Mortgage loans						$ (15,104)		$ (21,593)
Proceeds from sale of:
Property, plant and equipment						$ 463,602		$ 321,680
Short term investments
Fixed maturities investments
Equity securities
Preferred stock
Real estate
Mortgage loans						$ 11,635		$ 23,214
Net cash used by investing activities						(591,697)		(402,146)
Cash flow from financing activities:
Borrowings from credit facilities						461,276		510,074
Principal repayments on credit facilities						(233,304)		(266,672)
Debt issuance costs						(5,957)		(9,697)
Capital lease payments						(110,202)		(65,478)
Employee Stock Ownership Plan						(1,559)		$ (184)
Securitization deposits						448
Common stock dividends paid						$ (78,374)
Investment contract deposits
Investment contract withdrawals
Net cash provided by (used in) financing activities						$ 32,328		$ 168,043
Effects of exchange rate on cash						(17,578)		(6,243)
Increase (decrease) in cash and cash equivalents						217,318		248,992
Cash and cash equivalents at the beginning of period						431,873		464,710
Cash and cash equivalents at the end of the period		$ 649,191		$ 713,702		649,191		713,702
Operating Segments [Member] | Property and Casualty Insurance [Member]
Cash flow from operating activities:
Net earnings		$ 4,076	[1]	$ 4,513	[2]	$ 12,229	[3]	$ 11,658	[4]
Earnings from consolidated entities							[3]		[4]
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation							[3]		[4]
Amortization of deferred policy acquisition costs			[1]		[2]		[5]		[6]
Change in allowance for losses on trade receivables							[3]		[4]
Change in allowance for inventory reserves							[3]		[4]
Net gain on sale of real and personal property							[3]		[4]
Net (gain) loss on sale of investments						$ (652)	[3]	$ (839)	[4]
Deferred income tax						5,321	[3]	4,983	[4]
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables						$ 12,077	[3]	$ 17,101	[4]
Inventories							[3]		[4]
Prepaid expenses							[3]		[4]
Capitalization of deferred policy acquisition costs							[3]		[4]
Other assets						$ 1,358	[3]	$ 1,088	[4]
Related party assets						291	[3]	(947)	[4]
Accounts payable and accrued expenses						822	[3]	(248)	[4]
Policy benefits and losses, claims and loss expenses payable						(15,402)	[3]	(21,913)	[4]
Other policyholders' funds and liabilities						$ (1,239)	[3]	$ 1,395	[4]
Deferred income							[3]		[4]
Related party liabilities						$ (169)	[3]	$ 285	[4]
Net cash provided by operating activities						$ 14,636	[3]	$ 12,563	[4]
Cash flow from investing activities:
Property, plant and equipment							[3]		[4]
Short term investments						$ (30,536)	[3]	$ (35,624)	[4]
Fixed maturities investments						$ (32,593)	[3]	(33,735)	[4]
Equity securities							[3]	(3,333)	[4]
Preferred stock						$ (5)	[3]	(5)	[4]
Real estate						(6)	[3]	(3,812)	[4]
Mortgage loans						$ (1,800)	[3]	$ (3,150)	[4]
Proceeds from sale of:
Property, plant and equipment							[3]		[4]
Short term investments						$ 31,816	[3]	$ 39,745	[4]
Fixed maturities investments						$ 19,428	[3]	17,794	[4]
Equity securities							[3]	$ 3,082	[4]
Preferred stock	[4]
Real estate	[4]
Mortgage loans						$ 4,447	[3]	$ 3,976	[4]
Net cash used by investing activities						$ (9,249)	[3]	$ (15,062)	[4]
Cash flow from financing activities:
Borrowings from credit facilities							[3]		[4]
Principal repayments on credit facilities							[3]		[4]
Debt issuance costs							[3]		[4]
Capital lease payments							[3]		[4]
Employee Stock Ownership Plan							[3]		[4]
Securitization deposits	[3]
Common stock dividends paid	[3]
Investment contract deposits							[3]		[4]
Investment contract withdrawals							[3]		[4]
Net cash provided by (used in) financing activities							[3]		[4]
Effects of exchange rate on cash							[3]		[4]
Increase (decrease) in cash and cash equivalents						$ 5,387	[3]	$ (2,499)	[4]
Cash and cash equivalents at the beginning of period						8,495	[7]	12,758	[4]
Cash and cash equivalents at the end of the period		$ 13,882	[8]	$ 10,259	[4]	13,882	[8]	10,259	[4]
Operating Segments [Member] | Life Insurance [Member]
Cash flow from operating activities:
Net earnings		5,014	[1]	5,575	[2]	$ 12,990	[3]	$ 14,105	[4]
Earnings from consolidated entities							[3]		[4]
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation							[3]		[4]
Amortization of deferred policy acquisition costs		5,138	[1]	4,722	[2]	$ 15,559	[5]	$ 13,196	[6]
Change in allowance for losses on trade receivables						$ (211)	[3]	$ (11)	[4]
Change in allowance for inventory reserves							[3]		[4]
Net gain on sale of real and personal property							[3]		[4]
Net (gain) loss on sale of investments						$ (3,127)	[3]	$ (2,415)	[4]
Deferred income tax						974	[3]	2,444	[4]
Net change in other operating assets and liabilities:
Reinsurance recoverables and trade receivables						$ 1,911	[3]	$ (6,080)	[4]
Inventories							[3]		[4]
Prepaid expenses							[3]		[4]
Capitalization of deferred policy acquisition costs						$ (24,803)	[3]	$ (20,158)	[4]
Other assets						$ 96	[3]	$ (846)	[4]
Related party assets							[3]		[4]
Accounts payable and accrued expenses						$ 19,798	[3]	$ 9,537	[4]
Policy benefits and losses, claims and loss expenses payable						7,666	[3]	8,949	[4]
Other policyholders' funds and liabilities						$ 679	[3]	$ 1,335	[4]
Deferred income							[3]		[4]
Related party liabilities						$ 43	[3]	$ 215	[4]
Net cash provided by operating activities						$ 31,575	[3]	$ 20,271	[4]
Cash flow from investing activities:
Property, plant and equipment							[3]		[4]
Short term investments						$ (361,147)	[3]	$ (167,394)	[4]
Fixed maturities investments						(286,071)	[3]	(148,089)	[4]
Equity securities						$ (1,315)	[3]	$ (426)	[4]
Preferred stock							[3]		[4]
Real estate						$ (17)	[3]	$ (7,516)	[4]
Mortgage loans						$ (82,645)	[3]	$ (12,622)	[4]
Proceeds from sale of:
Property, plant and equipment							[3]		[4]
Short term investments						$ 369,028	[3]	$ 180,865	[4]
Fixed maturities investments						116,299	[3]	$ 57,578	[4]
Equity securities						808	[3]		[4]
Preferred stock	[4]							$ 2,027
Real estate	[4]							396
Mortgage loans						18,059	[3]	6,002	[4]
Net cash used by investing activities						(227,001)	[3]	$ (89,179)	[4]
Cash flow from financing activities:
Borrowings from credit facilities						47,000	[3]		[4]
Principal repayments on credit facilities						$ (47,000)	[3]		[4]
Debt issuance costs							[3]		[4]
Capital lease payments							[3]		[4]
Employee Stock Ownership Plan							[3]		[4]
Securitization deposits	[3]
Common stock dividends paid	[3]
Investment contract deposits						$ 246,756	[3]	$ 94,979	[4]
Investment contract withdrawals						(41,258)	[3]	(38,653)	[4]
Net cash provided by (used in) financing activities						$ 205,498	[3]	$ 56,326	[4]
Effects of exchange rate on cash							[3]		[4]
Increase (decrease) in cash and cash equivalents						$ 10,072	[3]	$ (12,582)	[4]
Cash and cash equivalents at the beginning of period						1,482	[7]	17,644	[4]
Cash and cash equivalents at the end of the period		11,554	[8]	5,062	[4]	11,554	[8]	5,062	[4]
Consolidation, Eliminations [Member]
Cash flow from operating activities:
Net earnings		$ (9,090)		$ (10,088)		(25,219)		(25,763)
Earnings from consolidated entities						$ 25,219		$ 25,763
Adjustments to reconcile net earnings to cash provided by operations:
Depreciation
Amortization of deferred policy acquisition costs
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								$ 243	[9]
Accounts payable and accrued expenses
Policy benefits and losses, claims and loss expenses payable
Other policyholders' funds and liabilities
Deferred income
Related party liabilities								$ (243)	[9]
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] Balances for the quarter ended September 30, 2015

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

[3] Balance for the period ended September 30, 2015

[4] Balance for the period ended September 30, 2014

[5] Balances for the nine months ended September 30, 2015

[6] Balances for the nine months ended September 30, 2014

[7] Balances as of December 31, 2014

[8] Balances as of September 30, 2015

[9] Elimination of intercompany investments