CONDENSED FINANCIAL STATEMENTS OF PEAPACK-GLADSTONE FINANCIAL CORPORATION (PARENT COMPANY ONLY) (STATEMENTS OF CONDITION) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash	$ 10,629	$ 6,591
Interest-earning deposits	642,591	201,492
Total cash and cash equivalents	653,322	208,185
Other assets	99,764	45,643
Total assets	5,890,442	5,182,879	$ 4,617,858
LIABILITIES
Subordinated debt	181,794	83,417
Other liabilities	121,488	65,076
Total liabilities	5,363,320	4,679,227
SHAREHOLDERS’ EQUITY
Common stock	16,958	16,733
Surplus	326,592	319,375
Treasury stock	(36,477)	(29,990)
Retained earnings	221,441	199,029
Accumulated other comprehensive loss	(1,392)	(1,495)
Total shareholders’ equity	527,122	503,652	$ 469,013	$ 403,678
Total liabilities and shareholders’ equity	5,890,442	5,182,879
Parent Company [Member]
ASSETS
Cash	117,670	13,931
Interest-earning deposits	523	523
Total cash and cash equivalents	118,193	14,454
Investment in subsidiary	593,162	567,964
Other assets	6	4,920
Total assets	711,361	587,338
LIABILITIES
Subordinated debt	181,794	83,417
Other liabilities	2,445	269
Total liabilities	184,239	83,686
SHAREHOLDERS’ EQUITY
Common stock	16,958	16,733
Surplus	326,592	319,375
Treasury stock	(36,477)	(29,990)
Retained earnings	221,441	199,029
Accumulated other comprehensive loss	(1,392)	(1,495)
Total shareholders’ equity	527,122	503,652
Total liabilities and shareholders’ equity	$ 711,361	$ 587,338