Loans Receivable, Net - Additional Information (Detail)		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2019 USD ($)	Jun. 30, 2019 USD ($) SecurityLoan	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) SecurityLoan	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans on non-accrual commercial real estate, multi-family, land, construction, commercial and industrial loans				$ 250,000
Impaired loan portfolio total		$ 28,567,000		28,567,000		$ 29,797,000
Allocation in allowance for loan losses		565,000		565,000		0
Average balance of impaired loans		31,500,000	$ 38,400,000	30,900,000	$ 41,300,000
Troubled debt restructured loans		26,100,000		26,100,000		26,500,000
Loans with non-accrual of interest		$ 17,796,000		$ 17,796,000		17,415,000
Number of residential mortgage loans | SecurityLoan		0		0
Non-accrual loan total troubled debt restructurings				$ 6,800,000		3,600,000
Specific reserves to loans accruing troubled debt restructurings		$ 464,000		464,000		0
Troubled debt restructured loans with accrual interest		19,300,000		19,300,000		22,900,000
Capital Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan and lease losses, loans acquired	$ 0
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans with non-accrual of interest		5,747,000		5,747,000		$ 7,389,000
Recorded investment in mortgage and consumer loans collateralized, foreclosure amount		1,800,000		1,800,000
Foreclosed property held		$ 112,000		$ 112,000