Parent Company Financial Statements (Statements of Condition) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Premises and equipment, net	$ 45,959	$ 23,886
Investment in subsidiaries:
Other assets	35,185	22,018
Total assets	3,709,871	2,789,853
LIABILITIES AND SHAREHOLDERS' EQUITY
Accrued interest and other liabilities	47,413	35,645
Shareholders’ equity	363,190	245,109	$ 231,096	$ 233,815
Total liabilities and shareholders’ equity	3,709,871	2,789,853
Parent Company [Member]
ASSETS
Cash	26,581	23,259
Investment in subsidiaries:
Bank	394,404	266,940
Acadia Trust	10,232	9,450
Receivable from subsidiaries	1,926	25
Other assets	14,475	12,600
Total assets	447,618	312,274
LIABILITIES AND SHAREHOLDERS' EQUITY
Due to subsidiaries	1,216	0
Subordinated debentures	59,126	44,024
Accrued interest and other liabilities	24,086	23,141
Shareholders’ equity	363,190	245,109
Total liabilities and shareholders’ equity	$ 447,618	$ 312,274