Washington Banking Company Information - Condensed Balance Sheets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 131,358	$ 107,573	$ 105,913	$ 81,687
Other assets	18,556	20,042
Assets	1,683,988	1,687,677
Subordinated Debt	25,774	25,774
Other liabilities	10,792	16,306
Liabilities	1,504,058	1,505,053
Common stock	86,714	85,707
Retained earnings	98,431	92,234
Accumulated other comprehensive (loss) income, net of tax	(5,215)	4,683
Stockholders' Equity Attributable to Parent	179,930	182,624	170,820	182,098
Liabilities and Equity	1,683,988	1,687,677
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	5,323	5,327	5,393	1,476
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	199,204	201,345
Other assets	1,284	1,747
Assets	205,811	208,419
Subordinated Debt	25,774	25,774
Other liabilities	107	21
Liabilities	25,881	25,795
Common stock	86,714	85,707
Retained earnings	98,431	92,234
Accumulated other comprehensive (loss) income, net of tax	(5,215)	4,683
Stockholders' Equity Attributable to Parent	179,930	182,624
Liabilities and Equity	$ 205,811	$ 208,419