Loans - Summary of Impaired Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
With an Allowance Recorded Related Allowance	$ 105	$ 98
Loans and Finance Receivables [Member]
Financing Receivable, Impaired [Line Items]
With No Related Allowing Recorded Investment	0	0
With No Related Allowing Unpaid Contractual Principal Balance	0	0
With an Allowance Recorded Investment	199	237
With an Allowance Recorded Unpaid Contractual Principal Balance	199	237
With an Allowance Recorded Related Allowance	105	98
Recorded Investment	199	237
Unpaid Contractual Principal Balance	199	237
Related Allowance	105	98
Loans and Finance Receivables [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
With No Related Allowing Recorded Investment	0	0
With No Related Allowing Unpaid Contractual Principal Balance	0	0
With an Allowance Recorded Investment	199	229
With an Allowance Recorded Unpaid Contractual Principal Balance	199	229
With an Allowance Recorded Related Allowance	105	92
Recorded Investment	199	229
Unpaid Contractual Principal Balance	199	229
Related Allowance	105	92
Loans and Finance Receivables [Member] | Consumer and Other Loans [Member]
Financing Receivable, Impaired [Line Items]
With No Related Allowing Recorded Investment		0
With No Related Allowing Unpaid Contractual Principal Balance		0
With an Allowance Recorded Investment		8
With an Allowance Recorded Unpaid Contractual Principal Balance		8
With an Allowance Recorded Related Allowance	$ 0	6
Recorded Investment		8
Unpaid Contractual Principal Balance		8
Related Allowance		$ 6