Accumulated Other Comprehensive Loss (Details) - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Changes in the components of accumulated other comprehensive income (loss)
Balance	$ 399,202,000	$ 390,774,000	$ 421,347,000	$ 436,083,000	$ 390,774,000	$ 436,083,000
Reclassifications from OCI to:
Other income	(564,000)		(819,000)		(928,000)	(1,443,000)
Revenue	(328,501,000)		(305,520,000)		(647,525,000)	(605,551,000)
Costs of revenue	238,584,000		216,346,000		473,319,000	432,827,000
Selling, general and administrative expenses	70,682,000		75,155,000		141,543,000	144,781,000
Interest expense	4,835,000		4,514,000		9,743,000	8,768,000
Less: comprehensive income (loss) attributable to noncontrolling interest, net of tax	35,000		200,000		365,000	(535,000)
Other comprehensive income (loss)	(8,585,000)	(1,194,000)		(14,526,000)
Other income (expense), net of tax	7,157,000		12,461,000		9,826,000	26,085,000
Comprehensive income (loss)			(10,492,000)
Balance	397,397,000	399,202,000	359,431,000	421,347,000	397,397,000	359,431,000
Investment securities, including noncontrolling interests
Changes in the components of accumulated other comprehensive income (loss)
OCI before reclassifications net of tax	(3,000)		(271,000)		(2,000)	(141,000)
Other Comprehensive Income (Loss), Tax
OCI before reclassifications, Tax	0		(2,000)		0	19,000
Investment securities, including noncontrolling interests | Other income (expense)
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	0		(1,000)		0	21,000
Investment securities, including noncontrolling interests | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassifications from OCI to:
Other income			(181,000)		2,000	(174,000)
Investment securities, noncontrolling interests
Reclassifications from OCI to:
Less : Noncontrolling interests, net of tax			28,000			21,000
Other Comprehensive Income (Loss), Tax
Noncontrolling interests, Tax	0		15,000		0	11
Accumulated Net Unrealized Investment Gain Loss
Changes in the components of accumulated other comprehensive income (loss)
Balance	15,000	12,000	199,000	69,000	12,000	69,000
Reclassifications from OCI to:
Comprehensive income (loss)	(3,000)		(424,000)			(294,000)
Balance	12,000	15,000	(225,000)	199,000	12,000	(225,000)
Other Comprehensive Income (Loss), Tax
Comprehensive income (loss), Tax	0		12,000		0	51,000
Currency Translation Adjustments, including noncontrolling interests
Changes in the components of accumulated other comprehensive income (loss)
OCI before reclassifications net of tax	(6,355,000)		(7,071,000)		(6,736,000)	(17,724,000)
Reclassifications from OCI to:
Less : Noncontrolling interests, net of tax	111,000		230,000		(26,000)	1,613,000
Accumulated Translation Adjustment [Member]
Changes in the components of accumulated other comprehensive income (loss)
Balance	(57,872,000)	(57,354,000)	(50,477,000)	(41,207,000)	(57,354,000)	(41,207,000)
Reclassifications from OCI to:
Comprehensive income (loss)	(6,244,000)		(6,841,000)		(6,762,000)	(16,111,000)
Balance	(64,116,000)	(57,872,000)	(57,318,000)	(50,477,000)	(64,116,000)	(57,318,000)
Cash Flow Hedges, including noncontrolling interests
Changes in the components of accumulated other comprehensive income (loss)
OCI before reclassifications net of tax	(46,000)		(4,440,000)		(247,000)	(7,946,000)
Other Comprehensive Income (Loss), Tax
OCI before reclassifications, Tax	(73,000)		(1,677,000)		(283,000)	(3,189,000)
Cash Flow Hedges, including noncontrolling interests | Revenue
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	0		282,000		7,000	406,000
Cash Flow Hedges, including noncontrolling interests | Costs of revenue
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	(240,000)		163,000		(316,000)	89,000
Cash Flow Hedges, including noncontrolling interests | Selling General And Administrative Expenses
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	(104,000)		85,000		(141,000)	45,000
Cash Flow Hedges, including noncontrolling interests | Interest expenses
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	(26,000)		(61,000)		(81,000)	(114,000)
Cash Flow Hedges, including noncontrolling interests | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassifications from OCI to:
Revenue			525,000		11,000	757,000
Costs of revenue	(879,000)		496,000		(1,208,000)	252,000
Selling, general and administrative expenses	(379,000)		258,000		(541,000)	128,000
Interest expense	(75,000)		(176,000)		(228,000)	(329,000)
Cash Flow Hedges, noncontrolling interests
Reclassifications from OCI to:
Less : Noncontrolling interests, net of tax			(11,000)		(1,000)	78,000
Other Comprehensive Income (Loss), Tax
Noncontrolling interests, Tax	0		(6,000)		0	42,000
Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges
Changes in the components of accumulated other comprehensive income (loss)
Balance	(796,000)	39,000	(1,831,000)	1,881,000	39,000	1,881,000
Reclassifications from OCI to:
Comprehensive income (loss)	(1,379,000)		(3,348,000)		(2,214,000)	(7,060,000)
Balance	(2,175,000)	(796,000)	(5,179,000)	(1,831,000)	(2,175,000)	(5,179,000)
Other Comprehensive Income (Loss), Tax
Comprehensive income (loss), Tax	(443,000)		(1,214,000)		(814,000)	(2,721,000)
Benefit plans, including noncontrolling interests
Changes in the components of accumulated other comprehensive income (loss)
OCI before reclassifications net of tax	(1,034,000)		(32,000)		(911,000)	(352,000)
Reclassifications from OCI to:
Other adjustments	75,000		93,000		72,000	151,000
Other Comprehensive Income (Loss), Tax
OCI before reclassifications, Tax	0		29,000		0	348,000
Benefit plans, prior service credit (cost), including noncontrolling interests | Other income (expense)
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	0		0		0	0
Benefit plans, prior service credit (cost), including noncontrolling interests | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassifications from OCI to:
Other income (expense), net of tax	7,000		14,000		13,000	28,000
Benefit plans, net actuarial gain (loss), including noncontrolling interest | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassifications from OCI to:
Other income (expense), net of tax	104,000		38,000		140,000	77,000
Benefit plans, noncontrolling interests
Reclassifications from OCI to:
Less : Noncontrolling interests, net of tax			8,000		(6,000)	9,000
Other Comprehensive Income (Loss), Tax
Noncontrolling interests, Tax	0		0		0	0
Accumulated Defined Benefit Plans Adjustment
Changes in the components of accumulated other comprehensive income (loss)
Balance	(1,928,000)	(2,084,000)	(1,632,000)	(1,424,000)	(2,084,000)	(1,424,000)
Reclassifications from OCI to:
Comprehensive income (loss)	(848,000)		121,000		(692,000)	(87,000)
Balance	(2,776,000)	(1,928,000)	(1,511,000)	(1,632,000)	(2,776,000)	(1,511,000)
Other Comprehensive Income (Loss), Tax
Comprehensive income (loss), Tax	0		29,000		0	348,000
Benefit plans, net actuarial gain (loss) | Other income (expense)
Other Comprehensive Income (Loss), Tax
Reclassifications from OCI, Tax	0		0		0	0
Accumulated Other Comprehensive Income
Changes in the components of accumulated other comprehensive income (loss)
Balance	(60,581,000)	(59,387,000)	(53,741,000)	(40,681,000)	(59,387,000)	(40,681,000)
Reclassifications from OCI to:
Other comprehensive income (loss)				(13,060,000)
Comprehensive income (loss)	(8,474,000)	(1,194,000)	(10,492,000)
Balance	$ (69,055,000)	$ (60,581,000)	$ (64,233,000)	$ (53,741,000)	$ (69,055,000)	$ (64,233,000)