CONDENSED FINANCIAL STATEMENTS OF PARENT ONLY - Parent Only Statement of Cash Flows (Details 2) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Cash flows from operating activities:                      
Net income $ 2,218 $ 2,835 $ 2,078 $ 2,390 $ 2,022 $ 1,741 $ 2,771 $ 1,601 $ 1,802 $ 9,325 $ 7,915
Adjustments to reconcile net income to net cash provided by (used in) operating activities:                      
Decrease in other assets 175       (611)         (613) 539
Increase (decrease) in other liabilities (1,166)       (664)         2,787 1,036
Cash flows from financing activities:                      
Purchase of treasury stock                   (215) (594)
Net increase (decrease) in cash and cash equivalents (4,887)       (25,369)         (19,076) 36,984
Cash and cash equivalents at beginning of year 28,613     $ 22,320 47,689       10,705 47,689 10,705
Cash and cash equivalents at end of year 23,726 28,613     22,320 47,689       28,613 47,689
PROVIDENT BANCORP, INC.                      
Cash flows from operating activities:                      
Net income                   9,325 7,915
Adjustments to reconcile net income to net cash provided by (used in) operating activities:                      
Equity in undistributed earnings of subsidiaries                   (9,289) (7,896)
Decrease in other assets                   191 191
Increase (decrease) in other liabilities                   13 (51)
Net cash provided by operating activities                   240 159
Cash flows from financing activities:                      
Purchase of treasury stock                   (215) (594)
Net cash used in financing activities                   (215) (594)
Net increase (decrease) in cash and cash equivalents                   25 (435)
Cash and cash equivalents at beginning of year $ 5,249       $ 5,224       $ 5,659 5,224 5,659
Cash and cash equivalents at end of year   $ 5,249       $ 5,224       $ 5,249 $ 5,224