Statement of Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) county Segment	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of counties in which entity provides services | county	15
Business segments | Segment	1
Equity investments	20.00%
Loans past due days	90 days
Excess impaired credits	$ 100,000
Other liabilities	$ 3,300,000
Software purchases and developed are capitalized and amortized on straight-line basis	7 years
Guaranteed Minimum Death Benefit [Member]
Summary Of Significant Accounting Policies [Line Items]
Other liabilities		$ 3,700,000