Junior Subordinated Debentures Boston Private Capital Trust I Terms (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Gain on repurchase of debt	$ 620,000	$ 3,444,000	$ 4,230,000
Boston Private Capital Trust I [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	105,000,000
Junior Subordinated Debt, Liquidation Price per Share	$ 50.00
Debt Instrument, Maturity Date	Oct. 01, 2034
Assets Held-in-trust	3,200,000	3,200,000
Debt Instrument, Decrease, Repayments	10,500,000	38,400,000	11,600,000
Debt Instrument, Frequency of Periodic Payment	quarterly
Debt Instrument, Interest Rate Terms	fixed
Debt Instrument, Interest Rate at Period End	4.875%
Debt Instrument, Call Feature	currently redeemable in whole at any time or in part from time to time if the closing price of BPFH’s common stock for 20 trading days in a period of 30 consecutive trading days ending on the trading day prior to the mailing of the redemption notice exceeds 130% of the then prevailing conversion price of the trust preferred securities
Debt Instrument, Convertible, Type of Equity Security	the Company’s common stock, $1.00 par value
Debt Instrument, Convertible, Conversion Price	$ 33.00
Debt Instrument, Convertible, Conversion Ratio	1.5402
Debt Instrument, Convertible, Number of Equity Instruments	685
Junior Subordinated Debentures [Member]
Debt Instrument [Line Items]
Debt Instrument, Decrease, Repayments	$ 36,500,000