Condensed Financial Statements of Parent Company - Statements of Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Condensed Income Statements Captions [Line Items]                      
Interest and dividends on investments                 $ 6,155 $ 5,740 $ 6,361
Total interest income                 72,755 64,601 58,203
Salaries and employee benefits                 31,441 29,892 27,584
Other                 6,521 6,468 6,477
Total non-interest expense $ 12,540 $ 11,902 $ 12,400 $ 12,135 $ 12,622 $ 11,444 $ 11,483 $ 11,219 48,977 46,768 45,333
Income before income tax expense 9,975 9,796 8,984 8,128 7,379 8,110 7,113 7,274 36,883 29,876 23,151
Income tax benefit (3,433) (3,548) (3,407) (2,885) (2,493) (2,844) (2,449) (2,476) (13,273) (10,262) (8,246)
Net income $ 6,542 $ 6,248 $ 5,577 $ 5,243 $ 4,886 $ 5,266 $ 4,664 $ 4,798 23,610 19,614 14,905
People’s Utah Bancorp, Inc.                      
Condensed Income Statements Captions [Line Items]                      
Dividend and other income from subsidiaries                 3,884 8,730 9,170
Interest and dividends on investments                 363 174  
Total interest income                 4,247 8,904 9,170
Salaries and employee benefits                 1,100 6,100 5,741
Other                 461 429 274
Total non-interest expense                 1,561 6,529 6,015
Income before income tax expense                 2,686 2,375 3,155
Income tax benefit                 624 216 289
Income (loss) from continuing operations                 3,310 2,591 3,444
Equity in undistributed net income of subsidiaries                 20,300 17,023 11,461
Net income                 $ 23,610 $ 19,614 $ 14,905