RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS - Impact of Adoption of ASC 606 on Financial Statements - Consolidated Statement of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 1,373,878	$ 1,264,958	$ 1,181,641	$ 1,165,864	$ 1,170,086	$ 1,124,100	$ 1,087,860		$ 1,085,814	$ 4,986,341	$ 4,467,860	$ 4,354,617
Costs of revenue:
Direct costs										3,304,053	2,978,608	2,934,804
Indirect costs and selling expenses										1,218,544	1,076,356	1,050,792
Depreciation and amortization										85,877	72,196	71,760
Total costs of revenue										4,608,474	4,127,160	4,057,356
Income from operations	81,096	94,908	102,263	99,600	80,340	104,794	88,262		67,304	377,867	340,700	297,261
Interest expense and other, net										49,958	42,036	48,642
Income before taxes										327,909	298,664	248,619
Income tax (benefit) expense										62,305	(2,507)	84,948
Net income	$ 50,030	$ 68,145	$ 68,596	$ 78,833	$ 51,831	$ 64,499	$ 142,795		$ 42,046	$ 265,604	$ 301,171	$ 163,671
Basic earnings per share	$ 2.01	$ 2.74	$ 2.76	$ 3.19	$ 2.10	$ 2.62	$ 5.80		$ 1.72	$ 10.70	$ 12.23	$ 6.71
Diluted earnings per share	$ 1.96	$ 2.69	$ 2.71	$ 3.10	$ 2.05	$ 2.56	$ 5.66		$ 1.67	$ 10.46	$ 11.93	$ 6.53
Under ASC 605
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue										$ 4,975,846
Costs of revenue:
Direct costs										3,304,053
Indirect costs and selling expenses										1,220,317
Depreciation and amortization										85,877
Total costs of revenue										4,610,247
Income from operations										365,599
Interest expense and other, net										49,958
Income before taxes										315,641
Income tax (benefit) expense										59,179
Net income										$ 256,462
Basic earnings per share										$ 10.33
Diluted earnings per share										$ 10.10
ASU 2014-09 | Effect of ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue										$ 10,495
Costs of revenue:
Indirect costs and selling expenses										(1,773)
Total costs of revenue										(1,773)
Income from operations										12,268
Income before taxes										12,268
Income tax (benefit) expense										3,126
Net income										$ 9,142
Basic earnings per share										$ 0.37
Diluted earnings per share										$ 0.36

[1] Net income for the second quarter of FY2019 includes a net benefit related to the TCJA. See Note 19.