Statutory Financial Information - Additional Information (Detail) - Wright Flood - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Statutory capital and surplus required	$ 7,500,000
Statutory capital and surplus	20,000,000.0	$ 19,400,000
Statutory net Income	$ 200,000	$ 4,500,000