Regulatory Capital Requirements (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Oct. 08, 2015	Dec. 31, 2014
Total risk-based capital:
Actual Regulatory Capital - Amount		$ 335,740		$ 269,497
Capital To Risk Weighted Assets		12.98%		15.16%
Minimum Regulatory Capital Required - Ratio		8.00%		8.00%
Tier 1 capital:
Actual Regulatory Capital - Amount		$ 299,552		$ 248,363
Actual Regulatory Capital - Ratio		11.58%		13.97%
Minimum Regulatory Capital Required - Ratio		6.00%		4.00%
Common equity tier I capital	[1]	$ 269,350
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount		$ 299,552		$ 248,363
Actual Regulatory Capital - Ratio		8.74%		9.26%
Minimum Regulatory Capital Required - Ratio		4.00%		4.00%
Common Equity Tier I Risk Based Capital Ratio	[1]	10.42%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	[1]	4.50%
Capital Conservation Buffer		2.50%
Value Of Trust Preferred Securities Included In Tier One Capital		$ 43,000
Subordinated Debt		59,126	$ 15,000	$ 44,024
Subsidiaries [Member]
Total risk-based capital:
Actual Regulatory Capital - Amount		$ 304,847		$ 244,351
Capital To Risk Weighted Assets		11.75%		13.85%
Minimum Regulatory Capital Required - Ratio		8.00%		8.00%
Minimum Regulatory Provision To Be Well Capitalized - Ratio		10.00%		10.00%
Tier 1 capital:
Actual Regulatory Capital - Amount		$ 283,659		$ 223,218
Actual Regulatory Capital - Ratio		10.93%		12.65%
Minimum Regulatory Capital Required - Ratio		6.00%		4.00%
Minimum Regulatory Provision To Be Well Capitalized - Ratio		8.00%		6.00%
Common equity tier I capital	[1]	$ 283,659
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount		$ 283,659		$ 223,218
Actual Regulatory Capital - Ratio		8.33%		8.38%
Minimum Regulatory Capital Required - Ratio		4.00%		4.00%
Minimum Regulatory Provision To Be Well Capitalized - Ratio		5.00%		5.00%
Common Equity Tier I Risk Based Capital Ratio	[1]	10.93%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	[1]	4.50%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	[1]	6.50%
Acadia Trust [Member]
Tier 1 capital:
Minimum Regulatory Capital Required - Amount		$ 2,500
Subordinated Debt [Member]
Tier 1 leverage capital ratio:
Subordinated Debt		$ 15,000

[1] (1) Common equity Tier I risk-based capital ratio was a new risk-based capital ratio implemented with Basel III on January 1, 2015.