LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Land and Land Development by State) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 3,418,445	$ 3,235,714
Percent of total loans	100.00%	100.00%
Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,235,847
Percent of total loans	65.40%
Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	711,774
Percent of total loans	20.80%
Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	293,225
Percent of total loans	8.60%
Land and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	86,145
Percent of total loans	100.00%
Land and land development [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	47,520
Percent of total loans	55.20%
Land and land development [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	35,410
Percent of total loans	41.10%
Land and land development [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,215
Percent of total loans	3.70%
Land and land development - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	75,695	77,010
Percent of total loans	2.20%	2.40%
Land and land development - residential [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	42,364
Land and land development - residential [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	32,046
Land and land development - residential [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,285
Land and land development - residential [Member] | Acquisition and development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	30,201
Land and land development - residential [Member] | Acquisition and development [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	16,886
Land and land development - residential [Member] | Acquisition and development [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	12,285
Land and land development - residential [Member] | Acquisition and development [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,030
Land and land development - residential [Member] | Improved land and lots [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	40,315
Land and land development - residential [Member] | Improved land and lots [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	20,621
Land and land development - residential [Member] | Improved land and lots [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	19,439
Land and land development - residential [Member] | Improved land and lots [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	255
Land and land development - residential [Member] | Unimproved land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	5,179
Land and land development - residential [Member] | Unimproved land [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,857
Land and land development - residential [Member] | Unimproved land [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	322
Land and land development - residential [Member] | Unimproved land [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	0
Land and land development - commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	10,450	13,982
Percent of total loans	0.30%	0.40%
Land and land development - commercial and industrial [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	5,156
Land and land development - commercial and industrial [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,364
Land and land development - commercial and industrial [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,930
Land and land development - commercial and industrial [Member] | Acquisition and development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	352
Land and land development - commercial and industrial [Member] | Acquisition and development [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	0
Land and land development - commercial and industrial [Member] | Acquisition and development [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	0
Land and land development - commercial and industrial [Member] | Acquisition and development [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	352
Land and land development - commercial and industrial [Member] | Improved land and lots [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,085
Land and land development - commercial and industrial [Member] | Improved land and lots [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,801
Land and land development - commercial and industrial [Member] | Improved land and lots [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	525
Land and land development - commercial and industrial [Member] | Improved land and lots [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	759
Land and land development - commercial and industrial [Member] | Unimproved land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	6,013
Land and land development - commercial and industrial [Member] | Unimproved land [Member] | Washington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,355
Land and land development - commercial and industrial [Member] | Unimproved land [Member] | Oregon [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,839
Land and land development - commercial and industrial [Member] | Unimproved land [Member] | Idaho [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 819