Business, Basis of Presentation and Significant Accounting Policies - Summary of Consolidated Statement of Balance Sheet Line Items, which Reflect Adoption of New Revenue Recognition Guidance (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets
Unbilled accounts receivable	$ 35,857	$ 38,307
Inventories, net	57,456		$ 73,073
Total current assets	350,383		330,260
Total assets	571,092		558,789
Stockholders' equity
Retained earnings (accumulated deficit)	(51,147)		(40,889)
Accumulated other comprehensive income (loss)	(20,059)		(33,114)
Total stockholders' equity (deficit)	(33,793)		(39,637)	$ (70,490)	$ (72,114)
Total liabilities and stockholders' deficit	571,092		$ 558,789
Adjustments [Member] | Accounting Standards Update 2014-09 [Member]
Current assets
Unbilled accounts receivable	35,857	38,307
Inventories, net	(26,659)	(29,823)
Total current assets	9,198
Total assets	9,198
Stockholders' equity
Retained earnings (accumulated deficit)	9,607
Accumulated other comprehensive income (loss)	(409)
Total stockholders' equity (deficit)	9,198	$ 8,484
Total liabilities and stockholders' deficit	9,198
Amounts Without Adoption of the New Revenue Standard [Member] | Accounting Standards Update 2014-09 [Member]
Current assets
Inventories, net	84,115
Total current assets	341,185
Total assets	561,894
Stockholders' equity
Retained earnings (accumulated deficit)	(60,754)
Accumulated other comprehensive income (loss)	(19,650)
Total stockholders' equity (deficit)	(42,991)
Total liabilities and stockholders' deficit	$ 561,894