LOANS AND PAYMENT PLAN RECEIVABLES, Loans Serviced for Others (FY) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) Quarter PSARate	Dec. 31, 2015 USD ($) PSARate	Dec. 31, 2014 USD ($)
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 1,658,993	$ 1,644,325
Custodial Escrow Balances	$ 18,900	21,800
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 year	$ 12,436	12,106	$ 13,710
Originated servicing rights capitalized	3,119	2,697	1,823
Amortization	(2,850)	(2,868)	(2,509)
Change in valuation allowance	966	501	(918)
Balance at end of year	13,671	12,436	12,106
Valuation allowance	2,306	3,272	3,773
Loans sold and serviced that have had servicing rights capitalized	1,657,996	1,643,086	$ 1,661,269
Fair value of capitalized mortgage loan servicing rights	$ 14,200	$ 12,900
Average coupon rate	4.20%	4.32%
Average servicing fee	0.256%	0.254%
Average discount rate	10.07%	10.04%
Average PSA Rate \| PSARate	175	203
Fannie Mae [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 944,703	$ 898,443
Freddie Mac [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	622,885	707,891
Ginnie Mae [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	85,290	37,884
Other [Member]
Mortgage loans serviced for others [Abstract]
Mortgage loans serviced	$ 6,115	$ 107

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Refers to additional required amount of capital required to be maintained as a percent of loans serviced.

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Refers to maximum number of consecutive quarterly losses recorded for profitability requirement.

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Refers to maximum percentage of decline in net worth for one consecutive quarter.

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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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Refers to percentage of decline in net worth during the period for profitability requirement.

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

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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 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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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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Fair value 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 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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