Income Taxes - Variation Between Expected and Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Statutory federal income tax (benefit) rate (percent)	35.00%	(35.00%)	35.00%
State income taxes (net of federal benefit) (percent)	5.70%	(1.20%)	0.90%
Qualified domestic production activities (percent)	(2.00%)	0.50%	(2.30%)
Research and development tax credits (percent)	(8.60%)	(2.90%)	(11.30%)
Goodwill impairment (percent)	0.00%	8.10%	0.00%
Changes in valuation allowance	0.90%	0.60%	8.50%
Non-deductible book expenses	0.20%	0.20%	0.90%
Changes in deferred tax assets (percent)	1.50%	0.10%	(5.00%)
Remeasurement of deferred taxes for changes in state tax law (percent)	0.00%	0.00%	(1.90%)
Changes in tax reserves (percent)	0.00%	0.10%	(0.70%)
Other (percent)	1.00%	(0.20%)	0.20%
Effective income tax (benefit) rate (percent)	33.70%	(29.70%)	24.30%