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Mortgage Banking Activities (Tables) | 9 Months Ended
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Sep. 30, 2018
Mortgage Banking [Abstract] |
Components of Residential Mortgage Loans Held For Sale [Table Text Block] |
|  | September 30, 2018 |  | December 31, 2017 |  | September 30, 2017
|  | Unpaid Principal Balance/ Notional |  | Fair Value |  | Unpaid Principal Balance/ Notional |  | Fair Value |  | Unpaid Principal Balance/ Notional |  | Fair Value
Residential mortgage loans held for sale |  | $ | 169,095 |  |  | $ | 169,226 |  |  | $ | 212,525 |  |  | $ | 215,113 |  |  | $ | 261,868 |  |  | $ | 265,783 |
Residential mortgage loan commitments |  | 197,752 |  |  | 5,027 |  |  | 222,919 |  |  | 6,523 |  |  | 334,337 |  |  | 9,066 |
Forward sales contracts |  | 330,876 |  |  | 1,613 |  |  | 380,159 |  |  | (258 | ) |  | 524,878 |  |  | 794 |
|  |  |  |  | $ | 175,866 |  |  |  |  |  | $ | 221,378 |  |  |  |  |  | $ | 275,643 |
Mortgage Banking Revenue [Table Text Block] | Mortgage banking revenue was as follows (in thousands):
|  | Three Months Ended September 30, |  | Nine Months Ended September 30,
|  | 2018 |  | 2017 |  | 2018 |  | 2017
Production revenue: |  |  |  |  |  |  |  |
Net realized gains on sale of mortgage loans |  | $ | 9,063 |  |  | $ | 12,041 |  |  | $ | 28,699 |  |  | $ | 32,443 |
Net change in unrealized gain on mortgage loans held for sale |  | (2,135 | ) |  | (1,492 | ) |  | (2,457 | ) |  | 3,335 |
Net change in the fair value of mortgage loan commitments |  | (2,446 | ) |  | (1,927 | ) |  | (1,496 | ) |  | (667 | )
Net change in the fair value of forward sales contracts |  | 2,768 |  |  | (293 | ) |  | 1,871 |  |  | (4,399 | )
Total production revenue |  | 7,250 |  |  | 8,329 |  |  | 26,617 |  |  | 30,712 |
Servicing revenue |  | 16,286 |  |  | 16,561 |  |  | 49,290 |  |  | 49,645 |
Total mortgage banking revenue |  | $ | 23,536 |  |  | $ | 24,890 |  |  | $ | 75,907 |  |  | $ | 80,357 |
Summary of Mortgage Servicing Rights [Table Text Block] | The following represents a summary of mortgage servicing rights (dollars in thousands):
|  | September 30, 2018 |  | December 31, 2017 |  | September 30, 2017
Number of residential mortgage loans serviced for others |  | 133,538 |  |  | 136,528 |  |  | 137,359 |
Outstanding principal balance of residential mortgage loans serviced for others |  | $ | 21,826,773 |  |  | $ | 22,046,632 |  |  | $ | 22,063,121 |
Weighted average interest rate |  | 3.97 | % |  | 3.94 | % |  | 3.95 | %
Remaining term (in months) |  | 295 |  |  | 297 |  |  | 298 |
Activity in Capitalized Mortgage Servicing Rights [Table Text Block] | The following represents activity in capitalized mortgage servicing rights (in thousands):
| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2018 |  | 2017 |  | 2018 |  | 2017
Beginning Balance | $ | 278,719 |  |  | $ | 245,239 |  |  | $ | 252,867 |  |  | $ | 247,073 |
Additions, net | 8,968 |  |  | 9,925 |  |  | 28,688 |  |  | 29,439 |
Change in fair value due to principal payments | (8,986 | ) |  | (8,667 | ) |  | (25,783 | ) |  | (24,928 | )
Change in fair value due to market assumption changes | 5,972 |  |  | (639 | ) |  | 28,901 |  |  | (5,726 | )
Ending Balance | $ | 284,673 |  |  | $ | 245,858 |  |  | $ | 284,673 |  |  | $ | 245,858 |
Assumptions to Value Mortgage Servicing Rights [Table Text Block] | Mortgage servicing rights are not traded in active markets. Fair value is determined by discounting the projected net cash flows. Significant market assumptions used to determine fair value based on significant unobservable inputs were as follows:
|  | September 30, 2018 |  | December 31, 2017 |  | September 30, 2017
Discount rate – risk-free rate plus a market premium |  | 9.95% |  | 9.84% |  | 9.84%
Prepayment rate - based upon loan interest rate, original term and loan type |  | 7.85%-15.04% |  | 8.72%-15.16% |  | 8.71%-15.43%
Loan servicing costs – annually per loan based upon loan type: |  |  |  |  |  |
Performing loans |  | $66-$92 |  | $65-$88 |  | $65-$120
Delinquent loans |  | $150-$500 |  | $150-$500 |  | $150-$500
Loans in foreclosure |  | $1,000-$4,000 |  | $1,000-$4,000 |  | $1,000-$4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life |  | 3.07% |  | 2.24% |  | 2.00%
Primary/secondary mortgage rate spread |  | 105 bps |  | 105 bps |  | 105 bps
Aging Status of Mortgage Loans Serviced For Others [Table Text Block] | The aging status of our mortgage loans serviced for others by investor at September 30, 2018 follows (in thousands):
|  |  |  | Past Due |  |
|  | Current |  | 30 to 59 Days |  | 60 to 89 Days |  | 90 Days or More |  | Total
FHLMC |  | $ | 7,804,568 |  |  | $ | 84,339 |  |  | $ | 14,825 |  |  | $ | 22,326 |  |  | $ | 7,926,058 |
FNMA |  | 6,495,003 |  |  | 91,699 |  |  | 14,698 |  |  | 17,281 |  |  | 6,618,681 |
GNMA |  | 6,569,093 |  |  | 245,827 |  |  | 54,429 |  |  | 16,867 |  |  | 6,886,216 |
Other |  | 388,107 |  |  | 5,290 |  |  | 529 |  |  | 1,892 |  |  | 395,818 |
Total |  | $ | 21,256,771 |  |  | $ | 427,155 |  |  | $ | 84,481 |  |  | $ | 58,366 |  |  | $ | 21,826,773 |

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- Definition Tabular disclosure of mortgage loans to individuals not classified as held for investment but are held-for-sale. + References No definition available. + Details
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- Definition Tabular disclosure of the activity in the balance of servicing assets (including a description of where changes in fair value are reported in the statement of income for each period for which results of operations are presented), including but not limited to, the following: beginning and ending balances, additions (for instance, through purchases of servicing assets), disposals, changes in fair value during the period resulting from changes in inputs or assumptions used in the valuation model, other changes in fair value along with a description of those changes, and other changes that affect the balance along with a description of those changes. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
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