Boston Private Financial Holdings, Inc. (Parent Company Only) Balance Sheet (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		$ 106,557	$ 238,694	$ 172,609	$ 191,881
Deferred income taxes, net		73,010	69,723
Other assets		130,753	121,179
Assets		7,970,474	7,542,508	6,797,874
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust		106,363	106,363
Deferred Income Tax Liabilities, Net		8,638	0
Other liabilities		119,683	111,468
Total liabilities		7,185,021	6,777,807
Stockholders' Equity Attributable to Noncontrolling Interest		21,133	21,481
Stockholders' Equity Attributable to Parent		764,320	743,220
Total liabilities, redeemable noncontrolling interests and shareholders’ equity		7,970,474	7,542,508
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		54,694	55,385	$ 44,593	$ 32,554
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		6,340	6,340
Deferred income taxes, net		0	1,460
Other assets		17,131	14,243
Assets		909,944	886,810
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust		106,363	106,363
Other liabilities		9,490	15,746
Total liabilities		124,491	122,109
Stockholders' Equity Attributable to Noncontrolling Interest	[1]	21,133	21,481
Stockholders' Equity Attributable to Parent		764,320	743,220
Total liabilities, redeemable noncontrolling interests and shareholders’ equity		909,944	886,810
Parent Company [Member] | Private Banking Segment [Member]
Condensed Financial Statements, Captions [Line Items]
Investments in and Advances to Affiliates, Balance, Principal Amount		694,517	671,204
Parent Company [Member] | Non Banking Segments [Member]
Condensed Financial Statements, Captions [Line Items]
Investments in and Advances to Affiliates, Balance, Principal Amount		$ 137,262	$ 138,178

[1] Includes noncontrolling interests and the maximum redemption value of redeemable noncontrolling interests.