Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes And Tax Related [Line Items]
Income tax expense (benefit)	$ 4,000,000		$ 9,030,000	$ (83,746,000)	$ 1,532,000
Deferred tax asset, valuation allowance	1,240,000	$ 5,368,000	1,240,000	5,368,000	140,915,000
Release valuation allowance		141,100,000	3,969,000	141,094,000
Total liabilities for tax obligation and associated interest and penalties	40,200,000	37,000,000	40,200,000	37,000,000
Income tax provisions for uncertain tax benefits	9,800,000	9,900,000	9,800,000	9,900,000
Interest accruals	28,200,000	24,900,000	28,200,000	24,900,000
Penalty accruals	2,200,000	2,200,000	2,200,000	2,200,000
Other tax long-term liabilities		36,300,000		36,300,000
Uncertain tax positions			3,227,000	3,128,000	1,529,000
Tax indemnification receivable	29,500,000	26,300,000	29,500,000	26,300,000
Tax indemnification income			2,855,000	8,367,000	1,055,000
Federal
Income Taxes And Tax Related [Line Items]
Net operating loss carryovers	207,200,000		207,200,000
Tax indemnification income				6,500,000
State Research Credit
Income Taxes And Tax Related [Line Items]
Tax credits	2,800,000		2,800,000
Massachusetts | Investment Tax Credits
Income Taxes And Tax Related [Line Items]
Tax credits	1,400,000		1,400,000
Net operating loss carryovers without expiration date	600,000		600,000
BMS
Income Taxes And Tax Related [Line Items]
Payments for state income tax settlements			0	0	700,000
Decrease in amount due from BMS included within other long-term assets			3,300,000	8,400,000	$ 1,300,000
Deferred Tax Assets
Income Taxes And Tax Related [Line Items]
Penalty accruals		$ 700,000		$ 700,000
2037 | Federal
Income Taxes And Tax Related [Line Items]
Net operating loss carryovers	$ 400,000		$ 400,000