Goodwill and Other Intangible Assets Goodwill Text (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 0		$ 0
Goodwill, Impairment Loss	$ 24,901		$ 9,528	$ 0
Goodwill, Impaired, Facts and Circumstances Leading to Impairment	The decline in fair value and the related goodwill impairment was related to the fair market value impacts of the Anchor sale transaction. Due to the limited interest and terms of the transaction that were required for a mutual agreement, the fair value obtained was substantially below the carrying value. The fair value was based on the terms of the sale transaction.
Long Lived Assets Held-for-sale, Description			The rationale for the sale was to better position the Company’s resources within the Southern California market.
Anchor [Member]
Goodwill [Line Items]
Proceeds from Sales of Business, Affiliate and Productive Assets	$ 32,000
Proceeds from Divestiture of Interest in Subsidiaries and Affiliates	15,000
Goodwill, Impairment Loss	$ 24,900
Long Lived Assets Held-for-sale, Description	The rationale for the sale is to focus the Company’s resources in businesses where we can offer holistic financial advice, along with integrated wealth management, trust, and private banking capabilities. This transaction will also generate additional capital for us to reinvest in a more focused Company.
Anchor [Member]
Goodwill [Line Items]
Goodwill, Impaired, Method for Fair Value Determination	In December 2017, the Company entered into an agreement to sell its entire ownership interest in Anchor in a transaction that will result in Anchor being majority owned by members of its management team. The Company will receive approximately $32 million of cash at closing and future revenue share payments that, at signing, have a net present value of approximately $15 million, subject to purchase price adjustments. The Company’s annual goodwill impairment test for Anchor resulted in a fourth quarter of 2017 goodwill impairment charge of $24.9 million.
Investment Managers Segment [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 24,901	[1]	$ 0
Wealth Management and Trust Segment [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0		$ 9,528
Goodwill, Impaired, Method for Fair Value Determination			Boston Private Wealth failed its Step 1 test and the Company performed a Step 2 test to determine the amount of goodwill impairment, if any. The estimated fair value of Boston Private Wealth was $68.0 million as compared to a carrying value of $76.9 million, resulting in a deficit of $8.9 million, or 11.6%. Because the estimated fair value of Boston Private Wealth was lower than its carrying value, the Company was required to perform a Step 2 valuation. The results of the Step 2 valuation indicated an implied fair value of goodwill of $34.8 million as compared to the book value of $44.3 million, or a deficiency of $9.5 million. The resulting deficiency was recorded as a goodwill impairment charge within operating expenses in the fourth quarter of 2016. As a result of the goodwill impairment, the carrying value of goodwill at Boston Private Wealth was reduced to $34.8 million.

[1] Remaining goodwill of Anchor is classified as held for sale as of December 31, 2017.