SUPPLEMENTAL GUARANTOR AND NON-GUARANTOR CONSOLIDATED FINANCIAL STATEMENTS - Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Condensed consolidating statements of cash flows
Net cash provided by (used in) operating activities	$ 1,149,909	$ 1,136,445	$ 794,034
Cash flows from investing activities:
Purchases of property and equipment, net of proceeds from disposal	(489,505)	(496,958)	(239,724)
Acquisition of businesses, net of cash acquired	(189,084)	(916,527)	(66,854)
Proceeds from divestitures of business, net of cash held in divested business	36,731	5,740	0
Other investing activities, net	(60,329)	11,369	64,362
Net cash used in investing activities	(702,187)	(1,396,376)	(242,216)
Cash flows from financing activities:
Proceeds from bank borrowings and long-term debt	312,741	884,702	319,542
Repayments of bank borrowings and long-term debt and capital lease obligations	(141,730)	(190,221)	(344,156)
Payments for early repurchase of long-term debt			0
Payments for repurchases of ordinary shares	(349,532)	(420,317)	(415,945)
Proceeds from exercise of stock options	12,438	61,278	23,508
Other financing activities, net	(76,024)	(85,800)	(98,966)
Net cash provided by (used in) financing activities	(242,107)	249,642	(516,017)
Effect of exchange rates on cash and cash equivalents	17,490	(10,549)	(1,121)
Net change in cash and cash equivalents	223,105	(20,838)	34,680
Cash and cash equivalents, beginning of year	1,607,570	1,628,408	1,593,728
Cash and cash equivalents, end of year	1,830,675	1,607,570	1,628,408
Eliminations
Condensed consolidating statements of cash flows
Net cash provided by (used in) operating activities		0	0
Cash flows from investing activities:
Purchases of property and equipment, net of proceeds from disposal	15	9	(15)
Investing cash flows from (to) affiliates	4,423,661	4,692,927	2,808,300
Net cash used in investing activities	4,423,676	4,692,936	2,808,285
Cash flows from financing activities:
Financing cash flows from (to) affiliates	(4,423,676)	(4,692,936)	(2,808,285)
Net cash provided by (used in) financing activities	(4,423,676)	(4,692,936)	(2,808,285)
Parent | Reportable legal entities
Condensed consolidating statements of cash flows
Net cash provided by (used in) operating activities	144,580	162,275	(73,356)
Cash flows from investing activities:
Investing cash flows from (to) affiliates	(1,142,988)	(1,596,210)	(1,703,983)
Other investing activities, net	(61,212)	(500)	(1,500)
Net cash used in investing activities	(1,204,200)	(1,596,710)	(1,705,483)
Cash flows from financing activities:
Proceeds from bank borrowings and long-term debt	204,879	824,618	303,000
Repayments of bank borrowings and long-term debt and capital lease obligations	(128,967)	(179,920)	(335,500)
Payments for repurchases of ordinary shares	(349,532)	(420,317)	(415,945)
Proceeds from exercise of stock options	12,438	61,278	23,497
Financing cash flows from (to) affiliates	1,164,543	1,240,145	2,420,952
Other financing activities, net	30,000
Net cash provided by (used in) financing activities	933,361	1,525,804	1,996,004
Effect of exchange rates on cash and cash equivalents	(47,055)	34,529	(246,908)
Net change in cash and cash equivalents	(173,314)	125,898	(29,743)
Cash and cash equivalents, beginning of year	734,869	608,971	638,714
Cash and cash equivalents, end of year	561,555	734,869	608,971
Guarantor Subsidiaries | Reportable legal entities
Condensed consolidating statements of cash flows
Net cash provided by (used in) operating activities	47,905	426,639	75,775
Cash flows from investing activities:
Purchases of property and equipment, net of proceeds from disposal	(182,132)	(151,383)	(85,876)
Acquisition of businesses, net of cash acquired	(69,998)	(809,272)	(20,589)
Proceeds from divestitures of business, net of cash held in divested business	30,655
Investing cash flows from (to) affiliates	(3,440,099)	(1,587,365)	(1,900,810)
Other investing activities, net	(12,429)	(31,011)	(13,821)
Net cash used in investing activities	(3,674,003)	(2,579,031)	(2,021,096)
Cash flows from financing activities:
Proceeds from bank borrowings and long-term debt	107,502		4,737
Repayments of bank borrowings and long-term debt and capital lease obligations	(6,695)	(3,059)	(3,127)
Financing cash flows from (to) affiliates	3,606,993	2,143,568	1,904,164
Other financing activities, net	(51,902)	(8,800)
Net cash provided by (used in) financing activities	3,655,898	2,131,709	1,905,774
Effect of exchange rates on cash and cash equivalents	(8,918)	612	(2,643)
Net change in cash and cash equivalents	20,882	(20,071)	(42,190)
Cash and cash equivalents, beginning of year	148,201	168,272	210,462
Cash and cash equivalents, end of year	169,083	148,201	168,272
Non-Guarantor Subsidiaries | Reportable legal entities
Condensed consolidating statements of cash flows
Net cash provided by (used in) operating activities	957,424	547,531	791,615
Cash flows from investing activities:
Purchases of property and equipment, net of proceeds from disposal	(307,388)	(345,584)	(153,833)
Acquisition of businesses, net of cash acquired	(119,086)	(107,255)	(46,265)
Proceeds from divestitures of business, net of cash held in divested business	6,076	5,740
Investing cash flows from (to) affiliates	159,426	(1,509,352)	796,493
Other investing activities, net	13,312	42,880	79,683
Net cash used in investing activities	(247,660)	(1,913,571)	676,078
Cash flows from financing activities:
Proceeds from bank borrowings and long-term debt	360	60,084	11,805
Repayments of bank borrowings and long-term debt and capital lease obligations	(6,068)	(7,242)	(5,529)
Proceeds from exercise of stock options			11
Financing cash flows from (to) affiliates	(347,860)	1,309,223	(1,516,831)
Other financing activities, net	(54,122)	(77,000)	(98,966)
Net cash provided by (used in) financing activities	(407,690)	1,285,065	(1,609,510)
Effect of exchange rates on cash and cash equivalents	73,463	(45,690)	248,430
Net change in cash and cash equivalents	375,537	(126,665)	106,613
Cash and cash equivalents, beginning of year	724,500	851,165	744,552
Cash and cash equivalents, end of year	$ 1,100,037	$ 724,500	$ 851,165