BUSINESS SEGMENT, CUSTOMER AND GEOGRAPHIC INFORMATION - Summarized Financial Information of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenue from external customers	$ 1,170,086	$ 1,124,100	$ 1,087,860		$ 1,085,814	$ 1,137,389	$ 1,086,418	$ 1,057,530	$ 1,073,280	$ 4,467,860	$ 4,354,617	$ 3,744,053
Net income	51,831	$ 64,499	$ 142,795		$ 42,046	44,231	$ 40,357	$ 42,420	$ 36,663	301,171	163,671	142,799
Net assets	2,106,887					1,793,721				2,106,887	1,793,721	1,607,313	$ 1,480,272
Goodwill	2,620,835					2,577,435				2,620,835	2,577,435	2,585,343
Total long-term assets	3,103,015					3,031,180				3,103,015	3,031,180	3,065,503
Total assets	4,034,206					3,911,082				4,034,206	3,911,082	3,987,341
Capital expenditures										41,594	43,268	20,835
Depreciation and amortization										72,196	71,760	64,752
Domestic Operations
Segment Reporting Information [Line Items]
Revenue from external customers										4,304,602	4,217,488	3,593,924
Net income										286,024	150,271	129,568
Net assets	1,948,768					1,652,736				1,948,768	1,652,736	1,476,924
Goodwill	2,514,520					2,479,496				2,514,520	2,479,496	2,487,148
Total long-term assets	2,975,620					2,912,488				2,975,620	2,912,488	2,943,896
Total assets	3,829,417					3,716,893				3,829,417	3,716,893	3,798,013
Capital expenditures										40,639	41,832	18,339
Depreciation and amortization										67,891	67,042	60,637
International Operations
Segment Reporting Information [Line Items]
Revenue from external customers										163,258	137,129	150,129
Net income										15,147	13,400	13,231
Net assets	158,119					140,985				158,119	140,985	130,389
Goodwill	106,315					97,939				106,315	97,939	98,195
Total long-term assets	127,395					118,692				127,395	118,692	121,607
Total assets	$ 204,789					$ 194,189				204,789	194,189	189,328
Capital expenditures										955	1,436	2,496
Depreciation and amortization										$ 4,305	$ 4,718	$ 4,115

[1] Net income for the second quarter of FY2018 includes a net benefit related to the TCJA. See Note 19.