Goodwill and Other Intangible Assets - Carrying Amount of Amortizable Intangible Assets and Related Accumulated Amortization (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 200,000	$ 400,000	$ 700,000	$ 1,200,000
Net Carrying Amount	4,428,000		$ 4,428,000		$ 2,216,000
Client Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			6 years 2 months
Gross Carrying Amount	18,628,000		$ 18,628,000		15,910,000
Accumulated Amortization	14,200,000		14,200,000		13,694,000
Net Carrying Amount	$ 4,428,000		$ 4,428,000		$ 2,216,000