Leases - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 31,710,000	$ 4,800,000
Operating lease, liability	33,699,000	$ 6,400,000
Deferred rent liabilities			$ 1,600,000
Operating leases that have not yet commenced	0
Operating lease cost	1,200,000
Cash paid for amounts included in the measurement of operating lease liabilities	$ 724,000
Operating lease, weighted-average remaining lease term	11 years 25 days
Operating lease, weighted-average incremental borrowing rate	6.04%
Nashville, TN [Member]
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 26,500,000
Operating lease, liability	26,500,000
Providigm, LLC [Member]
Lessee, Lease, Description [Line Items]
Right-of-use assets	1,200,000
Operating lease, liability	$ 1,200,000