Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2011
Basis of Pres and Saps [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Basis of Presentation and Summary of Significant Accounting Policies Boston Private Financial Holdings, Inc. (the “Company” or “BPFH”), is a bank holding company with three reportable segments: Private Banking, Investment Management, and Wealth Advisory. On March 31, 2011, Boston Private Bank & Trust Company, a wholly owned subsidiary of the Company, received regulatory approval from the Federal Deposit Insurance Corporation (the "FDIC") to merge, as the surviving bank, with Borel Private Bank & Trust Company ("Borel"), First Private Bank & Trust ("FPB"), and Charter Private Bank ("Charter"), all of which were also wholly owned subsidiaries of the Company. Boston Private Bank & Trust Company also received approval from the Massachusetts Commissioner of Banks for the merger on March 28, 2011. The bank merger was completed on May 27, 2011, and the four Private Banking affiliates began operating as a single, consolidated bank under one charter. Following the merger, Boston Private Bank & Trust Company, the surviving bank (the “Bank” or “Boston Private Bank”), operates primarily in four geographic markets: New England, San Francisco Bay, Southern California, and the Pacific Northwest. The Bank currently conducts business under the name of Boston Private Bank & Trust Company in its New England, Southern California, and Pacific Northwest markets. In the San Francisco Bay, the Bank conducts business under the name of Borel Private Bank & Trust Company, A Division of Boston Private Bank & Trust Company. The Company continues to implement an integration plan. Prior to May 27, 2011, the four banks operated as separate affiliates of BPFH. The Investment Management segment has two consolidated affiliate partners, consisting of Dalton, Greiner, Hartman, Maher & Co., LLC (“DGHM”) and Anchor Capital Holdings, LLC (“Anchor”) (together, the “Investment Managers”). The Wealth Advisory segment has three consolidated affiliate partners, consisting of KLS Professional Advisors Group, LLC (“KLS”), Bingham, Osborn & Scarborough, LLC (“BOS”), and Davidson Trust Company (“DTC”) (together, the “Wealth Advisors”). In addition, at December 31, 2010, the Company held an equity interest in Coldstream Holdings, Inc. of approximately 45%, which it sold in January 2011. The Company conducts substantially all of its business through its three reportable segments. All significant intercompany accounts and transactions have been eliminated in consolidation. The unaudited interim consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”), and include all necessary adjustments of a normal recurring nature, which in the opinion of management, are required for a fair presentation of the results of operations and financial condition of the Company. The interim results of consolidated operations are not necessarily indicative of the results for the entire year. The information in this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Annual Report on Form 10-K, as amended, for the year ended December 31, 2010 filed with the Securities and Exchange Commission (“SEC”). Prior period amounts are reclassified whenever necessary to conform to the current period presentation. The Company’s significant accounting policies are described in Part II. Item 8. “Financial Statements and Supplementary Data - Note 1: Basis of Presentation and Summary of Significant Accounting Policies” in the Company’s Annual Report on Form 10-K, as amended, for the year ended December 31, 2010 filed with the SEC. For interim reporting purposes, the Company follows the same significant accounting policies.

Basis of Presentation and Summary of Significant Accounting Policies

Boston Private Financial Holdings, Inc. (the “Company” or “BPFH”), is a bank holding company with three reportable segments: Private Banking, Investment Management, and Wealth Advisory.

On March 31, 2011, Boston Private Bank & Trust Company, a wholly owned subsidiary of the Company, received regulatory approval from the Federal Deposit Insurance Corporation (the "FDIC") to merge, as the surviving bank, with Borel Private Bank & Trust Company ("Borel"), First Private Bank & Trust ("FPB"), and Charter Private Bank ("Charter"), all of which were also wholly owned subsidiaries of the Company. Boston Private Bank & Trust Company also received approval from the Massachusetts Commissioner of Banks for the merger on March 28, 2011. The bank merger was completed on May 27, 2011, and the four Private Banking affiliates began operating as a single, consolidated bank under one charter.

Following the merger, Boston Private Bank & Trust Company, the surviving bank (the “Bank” or “Boston Private Bank”), operates primarily in four geographic markets: New England, San Francisco Bay, Southern California, and the Pacific Northwest. The Bank currently conducts business under the name of Boston Private Bank & Trust Company in its New England, Southern California, and Pacific Northwest markets. In the San Francisco Bay, the Bank conducts business under the name of Borel Private Bank & Trust Company, A Division of Boston Private Bank & Trust Company. The Company continues to implement an integration plan. Prior to May 27, 2011, the four banks operated as separate affiliates of BPFH.

The Investment Management segment has two consolidated affiliate partners, consisting of Dalton, Greiner, Hartman, Maher & Co., LLC (“DGHM”) and Anchor Capital Holdings, LLC (“Anchor”) (together, the “Investment Managers”).

The Wealth Advisory segment has three consolidated affiliate partners, consisting of KLS Professional Advisors Group, LLC (“KLS”), Bingham, Osborn & Scarborough, LLC (“BOS”), and Davidson Trust Company (“DTC”) (together, the “Wealth Advisors”). In addition, at December 31, 2010, the Company held an equity interest in Coldstream Holdings, Inc. of approximately 45%, which it sold in January 2011.

The Company conducts substantially all of its business through its three reportable segments. All significant intercompany accounts and transactions have been eliminated in consolidation.

The unaudited interim consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”), and include all necessary adjustments of a normal recurring nature, which in the opinion of management, are required for a fair presentation of the results of operations and financial condition of the Company. The interim results of consolidated operations are not necessarily indicative of the results for the entire year.

The information in this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Annual Report on Form 10-K, as amended, for the year ended December 31, 2010 filed with the Securities and Exchange Commission (“SEC”). Prior period amounts are reclassified whenever necessary to conform to the current period presentation.

The Company’s significant accounting policies are described in Part II. Item 8. “Financial Statements and Supplementary Data - Note 1: Basis of Presentation and Summary of Significant Accounting Policies” in the Company’s Annual Report on Form 10-K, as amended, for the year ended December 31, 2010 filed with the SEC. For interim reporting purposes, the Company follows the same significant accounting policies.