Recent Accounting Pronouncements - Impact of Adoption of ASC 606 on Financial Statements - Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jul. 01, 2018	Jun. 30, 2018
ASSETS
Accounts receivable, net	$ 945,564	$ 827,325	$ 806,871
Prepaid expenses and other current assets	73,074	60,468	58,126
Other long-term assets	43,395	43,098	39,175
LIABILITIES AND SHAREHOLDERS’ EQUITY
Accounts payable	135,311		82,017
Other accrued expenses and current liabilities	186,175	152,814	150,602
Deferred income taxes	217,778	207,519	200,880
Other long-term liabilities	82,139	85,285	85,187
Retained earnings	2,223,393	2,144,560	2,126,790
Under ASC 605
ASSETS
Accounts receivable, net	919,394		806,871
Prepaid expenses and other current assets	70,767		58,126
Other long-term assets	39,495		39,175
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other accrued expenses and current liabilities	183,350		150,602
Deferred income taxes	211,307		200,880
Other long-term liabilities	82,139		85,187
Retained earnings	2,200,312		$ 2,126,790
ASU 2014-09 | Adjustments Due to ASC 606
ASSETS
Accounts receivable, net	26,170	20,454
Prepaid expenses and other current assets	2,307	2,342
Other long-term assets	3,900	3,923
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other accrued expenses and current liabilities	2,825	2,212
Deferred income taxes	6,471	6,639
Other long-term liabilities		98
Retained earnings	$ 23,081	$ 17,770