Boston Private Financial Holdings, Inc. (Parent Company Only) Income Statement (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Gain on repurchase of debt																	$ 620,000		$ 3,444,000		$ 4,230,000
Noninterest Income, Other Operating Income																	2,414,000		450,000		1,610,000
Revenues																	310,359,000		298,242,000		297,865,000
Salaries and employee benefits																	140,761,000		143,852,000		142,872,000
Professional services																	12,109,000		13,113,000		16,810,000
Interest Expense, Junior Subordinated Debentures																	4,408,000		6,258,000		7,434,000
Restructuring expense																	0		5,911,000		8,055,000
Other																	17,631,000		17,645,000		14,553,000
Income before income taxes	24,181,000	[1]	26,443,000	[1]	30,067,000	[1]	18,308,000	[1]	18,103,000	[1]	20,820,000	[1]	17,570,000	[1]	12,595,000	[1]	98,999,000		69,088,000		50,381,000
Income tax benefit	7,303,000	[1]	8,557,000	[1]	10,551,000	[1]	5,897,000	[1]	6,115,000	[1]	5,124,000	[1]	5,240,000	[1]	3,851,000	[1]	32,308,000	[2]	20,330,000	[2]	14,280,000	[2]
Income from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,968,000	[1]	1,321,000	[1]	2,781,000	[1]	1,722,000	[1]	1,819,000	[1]	1,672,000	[1]	2,590,000	[1]	1,554,000	[1]	7,792,000		7,635,000		6,184,000
Net income attributable to the Company	17,668,000	[1]	18,336,000	[1]	21,328,000	[1]	13,203,000	[1]	13,092,000	[1]	16,513,000	[1]	14,161,000	[1]	9,505,000	[1]	70,535,000		53,271,000		39,137,000
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Interest Income, Operating																	140,000		218,000		323,000
Gain on repurchase of debt																	620,000		3,444,000		4,230,000
Noninterest Income, Other Operating Income																	496,000		306,000		1,147,000
Revenues																	53,201,000		31,827,000		36,347,000
Salaries and employee benefits																	11,888,000		15,066,000		15,286,000
Professional services																	3,064,000		3,224,000		4,184,000
Interest Expense, Junior Subordinated Debentures																	4,408,000		6,258,000		7,474,000
Restructuring expense																	0		1,897,000	[3]	2,609,000	[3]
Other																	3,749,000		3,093,000		3,664,000
Operating Expenses																	23,109,000		29,538,000		33,217,000
Income before income taxes																	30,092,000		2,289,000		3,130,000
Income tax benefit																	(8,688,000)		(11,820,000)		(11,659,000)
Income from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest																	7,792,000		7,635,000		6,184,000
Net income attributable to the Company																	46,572,000		21,744,000		20,973,000
Severance Costs																	1,900,000		400,000
Parent Company [Member] | Private Banking Segment [Member]
Condensed Financial Statements, Captions [Line Items]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries																	27,900,000		10,300,000		7,400,000
Net income attributable to the Company																	(64,628,000)		(51,212,000)		(40,119,000)
Parent Company [Member] | Non Banking Segments [Member]
Condensed Financial Statements, Captions [Line Items]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries																	24,045,000		17,559,000		23,247,000
Net income attributable to the Company																	(11,280,000)		(8,174,000)		(8,777,000)
Private Banking, Investment Management, and Wealth Advisory Segments [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income attributable to the Company																	$ 23,963,000		$ 31,527,000		$ 18,164,000

[1] Due to rounding, the sum of the four quarters may not add to the year to date total.

[2] The Company’s effective tax rate for 2013, 2012, and 2011 are not consistent due to earnings from tax-exempt investments, non-deductible compensation, state and local taxes, income tax credits and income attributable to noncontrolling interests having a different impact on the effective tax rate due primarily to the different levels of income before taxes in years 2013, 2012, and 2011. See Part II. Item 8. “Financial Statements and Supplementary Data - Note 17: Income Taxes” for additional details.

[3] Includes severance expense of $1.9 million and $0.4 million for the years ended December 31, 2012 and 2011, respectively.