Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Aug. 22, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2013	Dec. 31, 2018
Loss Contingencies [Line Items]
Incentive awarded to the company by the State of Connecticut, total				$ 11,500
Incentive awarded to the company by the State of Connecticut, non-interest bearing loans				8,000
Incentive awarded to the company by the State of Connecticut, grants				$ 3,500
Non-interest bearing incentive loan term		10 years
Forgiveness awarded to the company by the state of Connecticut		$ 7,000
Incentive awarded to the company by the State of Connecticut, other revenue recognized		300	$ 400
Incentive awarded to the company by the State of Connecticut, deferred revenue included in other liabilities		$ 4,400			$ 4,700
The Hartford
Loss Contingencies [Line Items]
Merger Termination Fee	$ 68,250