Summarize Impact of ASC 606 to Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
ASSETS
Accounts receivable, less allowance for doubtful accounts	$ 352,476		$ 272,783
Inventories, net	154,705		107,525
Deferred tax assets	70,772		84,026
LIABILITIES
Deferred revenue and customer advances	77,953		83,614
Income taxes payable	24,603		59,055
Long-term deferred revenue and customer advances	29,387		30,127
Shareholders' equity
Accumulated deficit	(23,243)		$ 272,013
ASU 2014-09
ASSETS
Accounts receivable, less allowance for doubtful accounts	321,271
Inventories, net	166,413
Deferred tax assets	67,088
LIABILITIES
Deferred revenue and customer advances	73,128	$ 76,638
Income taxes payable	20,332
Long-term deferred revenue and customer advances	19,419	20,848
Shareholders' equity
Accumulated deficit	(27,360)
ASU 2014-09 | Adjustments to Recognize Under Legacy GAAP
ASSETS
Accounts receivable, less allowance for doubtful accounts	(31,205)
Inventories, net	11,708
Deferred tax assets	(3,684)
LIABILITIES
Deferred revenue and customer advances	(4,825)	1,315
Income taxes payable	(4,271)
Long-term deferred revenue and customer advances	(9,968)	$ 8,539
Shareholders' equity
Accumulated deficit	$ (4,117)