Regulatory Capital Requirements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Total risk-based capital:
Actual Regulatory Capital - Amount	$ 269,497	$ 256,648
Capital To Risk Weighted Assets	15.16%	16.45%
Minimum Regulatory Capital Required - Amount	142,227	124,787
Minimum Regulatory Capital Required - Ratio	8.00%	8.00%
Actual Regulatory Capital - Amount	177,783	155,983
Minimum Regulatory Provision To Be Well Capitalized - Ratio	10.00%	10.00%
Tier 1 capital:
Actual Regulatory Capital - Amount	248,363	237,124
Actual Regulatory Capital - Ratio	13.97%	15.20%
Minimum Regulatory Capital Required - Amount	71,113	62,393
Minimum Regulatory Capital Required - Ratio	4.00%	4.00%
Minimum Regulatory Provision To Be Well Capitalized - Amount	106,670	93,590
Minimum Regulatory Provision To Be Well Capitalized - Ratio	6.00%	6.00%
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount	248,363	237,124
Actual Regulatory Capital - Ratio	9.26%	9.43%
Minimum Regulatory Capital Required - Amount	109,201	102,551
Minimum Regulatory Capital Required - Ratio	4.00%	4.00%
Minimum Regulatory Provision To Be Well Capitalized - Amount	136,501	128,188
Minimum Regulatory Provision To Be Well Capitalized - Ratio	5.00%	5.00%
Subsidiaries [Member]
Total risk-based capital:
Actual Regulatory Capital - Amount	244,351	228,375
Capital To Risk Weighted Assets	13.85%	14.80%
Minimum Regulatory Capital Required - Amount	141,120	123,421
Minimum Regulatory Capital Required - Ratio	8.00%	8.00%
Actual Regulatory Capital - Amount	176,400	154,276
Minimum Regulatory Provision To Be Well Capitalized - Ratio	10.00%	10.00%
Tier 1 capital:
Actual Regulatory Capital - Amount	223,218	209,062
Actual Regulatory Capital - Ratio	12.65%	13.55%
Minimum Regulatory Capital Required - Amount	70,560	61,710
Minimum Regulatory Capital Required - Ratio	4.00%	4.00%
Minimum Regulatory Provision To Be Well Capitalized - Amount	105,840	92,566
Minimum Regulatory Provision To Be Well Capitalized - Ratio	6.00%	6.00%
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount	223,218	209,062
Actual Regulatory Capital - Ratio	8.38%	8.39%
Minimum Regulatory Capital Required - Amount	108,288	101,439
Minimum Regulatory Capital Required - Ratio	4.00%	4.00%
Minimum Regulatory Provision To Be Well Capitalized - Amount	135,360	126,798
Minimum Regulatory Provision To Be Well Capitalized - Ratio	5.00%	5.00%
Acadia Trust [Member]
Tier 1 capital:
Minimum Regulatory Capital Required - Amount	$ 2,500