Accrued Restructuring - Narrative (Detail)	3 Months Ended			9 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2016 Employee	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Accrued Liabilities, Current	$ 3,609,000					$ 3,874,000
Restructuring charges	0		$ 758,000
Remaining restructuring charges	0		379,000		$ 249,000	$ 0
Payments for Restructuring	$ 0		(628,000)
Q2 2015 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges					$ 4,200,000
Reduction in headcount, percent		14.00%
Remaining restructuring charges			0.2
Two Thousand Sixteen Q1 Restructuring Plan [Member] [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring plan, number of positions | Employee				57
Restructuring charges		$ 0
Reduction in headcount, percent		30.00%
Remaining restructuring charges			$ 0.2