LOANS AND PAYMENT PLAN RECEIVABLES, Loans Serviced for Others (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) Quarter PSARate	Dec. 31, 2017 USD ($) PSARate	Dec. 31, 2016 USD ($)
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 2,333,745	$ 1,816,437
Custodial deposit accounts	$ 22,000	20,700
Maximum number of consecutive quarterly losses recorded for profitability requirement \| Quarter	4
Percentage of decline in net worth during the period	30.00%
Maximum percentage of decline in net worth for one consecutive quarter	25.00%
Maximum percentage of decline in net worth for two consecutive quarters	40.00%
Highest level of capital, Amount	$ 2,500
Highest level of capital	0.25%
Analysis of capitalized mortgage loan servicing rights [Abstract]
Balance at beginning of period	$ 15,699
Balance at beginning of period		13,671	$ 12,436
Change in accounting (see note #1)	0	542	0
Balance at beginning of period, as adjusted	15,699	14,213	12,436
Originated servicing rights capitalized	4,977	4,230	3,119
Servicing rights acquired	3,047	0	0
Amortization	0	0	(2,850)
Change in valuation allowance	0	0	966
Change in fair value due to price	191	(718)	0
Change in fair value due to pay downs	(2,514)	(2,026)	0
Balance at end of year			13,671
Balance at end of year	21,400	15,699
Valuation allowance	0	0	2,306
Loans sold and serviced that have had servicing rights capitalized	$ 2,333,081	$ 1,815,668	$ 1,657,996
Average coupon rate	4.23%	4.17%
Average servicing fee	0.258%	0.258%
Average discount rate	10.15%	10.11%
Average PSA Rate \| PSARate	182	169
Fannie Mae [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 1,350,703	$ 1,001,388
Freddie Mac [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	712,740	637,204
Ginnie Mae [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	165,467	130,284
FHLB [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	78,687	47,527
Other [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 26,148	$ 34

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Refers to maximum percentage of decline in net worth for two consecutive quarters.

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The carrying amount of mortgage loans on real estate that were being serviced for others at period end.

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This is the principal amount outstanding for mortgage loans serviced for others.

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Adjusted amortized amount of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Amount of increase (decrease) to contract to service financial assets due to a change in accounting.

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Amount of increase (decrease) in fair value of servicing assets due to changes in price.

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Amount of increase (decrease) in fair value of servicing assets due to pay downs.

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The average coupon rate used to estimate the fair value of servicing assets and servicing liabilities.

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The average servicing fee rate used to estimate the fair value of servicing assets and servicing liabilities.

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The average PSA rate used to estimate the fair value of servicing assets and servicing liabilities.

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The value of servicing assets acquired during the current period through an acquisition.

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The periodic amortization (in proportion to and over the period of estimated net servicing income or loss) of capitalized servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of increase (decrease) in the amortized amount from a decrease (increase) in the valuation allowance applied to the servicing asset for a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

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