Consolidated Statements of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Series D [Member]	Scottdale Bank and Trust Company [Member]	First Priority Financial Corp. [Member]	First Priority Financial Corp. [Member] Series D [Member]	Preferred Stock [Member]	Preferred Stock [Member] First Priority Financial Corp. [Member] Series D [Member]	Common Stock [Member]	Common Stock [Member] Scottdale Bank and Trust Company [Member]	Common Stock [Member] First Priority Financial Corp. [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Scottdale Bank and Trust Company [Member]	Additional Paid-in Capital [Member] First Priority Financial Corp. [Member]	Retained Earnings [Member]	Retained Earnings [Member] Series D [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2017	$ 75,703							$ 4,242			$ 40,970			$ 32,565		$ (2,074)
Impact of adoption of new accounting standard (ASU 2016-01 [Member]) at Dec. 31, 2017	(9)													(44)		35
Balance at Dec. 31, 2017	75,694							4,242			40,970			32,521		(2,039)
Net income	1,004													1,004
Total other comprehensive (loss) income, net of taxes	(1,867)															(1,867)
Stock issued to shareholders			$ 64,181						$ 1,879			$ 62,302
Employee Stock Purchase Plan	24							1			23
Director Stock Purchase Plan	30							1			29
Restricted stock activity	58										58
Balance at Mar. 31, 2018	139,124							6,123			103,382			33,525		(3,906)
Balance at Dec. 31, 2017	75,703							4,242			40,970			32,565		(2,074)
Impact of adoption of new accounting standard (ASU 2016-01 [Member]) at Dec. 31, 2017	(9)													(44)		35
Balance at Dec. 31, 2017	75,694							4,242			40,970			32,521		(2,039)
Net income	5,947
Total other comprehensive (loss) income, net of taxes	(1,652)
Balance at Sep. 30, 2018	221,835					$ 3,404		8,457			177,421			36,244		(3,691)
Balance at Mar. 31, 2018	139,124							6,123			103,382			33,525		(3,906)
Net income	2,779													2,779
Total other comprehensive (loss) income, net of taxes	672															672
Common stock dividends declared	(918)													(918)
Employee Stock Purchase Plan	32							1			31
Director Stock Purchase Plan	31							1			30
Restricted stock activity	55										55
Balance at Jun. 30, 2018	141,775							6,125			103,498			35,386		(3,234)
Net income	2,164													2,164
Total other comprehensive (loss) income, net of taxes	(457)															(457)
Stock issued to shareholders				$ 76,122	$ 3,404		$ 3,404			$ 2,321			$ 73,801
Common stock dividends declared	(1,268)													(1,268)
Preferred stock dividends		$ (38)													$ (38)
Employee Stock Purchase Plan	29							1			28
Director Stock Purchase Plan	31							1			30
Restricted stock activity	73							9			64
Balance at Sep. 30, 2018	221,835					$ 3,404		8,457			177,421			36,244		(3,691)
Balance at Dec. 31, 2018	223,209							8,460			177,565			39,562		(2,378)
Impact of adoption of new accounting standard (ASU 2016-01 [Member]) at Dec. 31, 2018	316													316
Balance at Dec. 31, 2018	223,525							8,460			177,565			39,878		(2,378)
Net income	4,077													4,077
Total other comprehensive (loss) income, net of taxes	1,807															1,807
Common stock dividends declared	(2,113)													(2,113)
Employee Stock Purchase Plan	28							1			27
Director Stock Purchase Plan	33							1			32
Restricted stock activity	80										80
Balance at Mar. 31, 2019	227,437							8,462			177,704			41,842		(571)
Balance at Dec. 31, 2018	223,209							8,460			177,565			39,562		(2,378)
Impact of adoption of new accounting standard (ASU 2016-01 [Member]) at Dec. 31, 2018	316													316
Balance at Dec. 31, 2018	223,525							8,460			177,565			39,878		(2,378)
Net income	13,293
Total other comprehensive (loss) income, net of taxes	2,509
Balance at Sep. 30, 2019	234,612							8,478			177,994			48,009		131
Balance at Mar. 31, 2019	227,437							8,462			177,704			41,842		(571)
Net income	4,403													4,403
Total other comprehensive (loss) income, net of taxes	797															797
Common stock dividends declared	(1,524)													(1,524)
Employee Stock Purchase Plan	36							2			34
Director Stock Purchase Plan	33							1			32
Restricted stock activity	80										80
Balance at Jun. 30, 2019	231,262							8,465			177,850			44,721		226
Net income	4,813													4,813
Total other comprehensive (loss) income, net of taxes	(95)															(95)
Common stock dividends declared	(1,525)													(1,525)
Employee Stock Purchase Plan	31							1			30
Director Stock Purchase Plan	35							1			34
Restricted stock activity	91							11			80
Balance at Sep. 30, 2019	$ 234,612							$ 8,478			$ 177,994			$ 48,009		$ 131