Borrowings (Securities Sold Under Agreement to Repurchase by Counterparties) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Borrowings	$ 328,748	$ 795,354
Securities Sold under Agreements to Repurchase [Member]
Debt Instrument [Line Items]
Borrowings	192,500	652,229
Fair Value of Underlying Collateral	205,483	700,498
Securities Sold under Agreements to Repurchase [Member] \| PR Money Market Fund
Debt Instrument [Line Items]
Borrowings	0	70,010
Fair Value of Underlying Collateral	0	74,538
Securities Sold under Agreements to Repurchase [Member] \| JP Morgan Chase Bank [Member]
Debt Instrument [Line Items]
Borrowings	82,500	350,219
Fair Value of Underlying Collateral	88,974	376,674
Securities Sold under Agreements to Repurchase [Member] \| FHLB [Member]
Debt Instrument [Line Items]
Borrowings	110,000	0
Fair Value of Underlying Collateral	116,509	0
Securities Sold under Agreements to Repurchase [Member] \| Credit Suisse LLC [Member]
Debt Instrument [Line Items]
Borrowings	0	232,000
Fair Value of Underlying Collateral	0	249,286
Securities Sold under Agreements to Repurchase [Member] \| Goldman Sachs [Member]
Debt Instrument [Line Items]
Borrowings	0	0
Fair Value of Underlying Collateral	$ 0	$ 0

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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The fair value, as of the date of each statement of financial position presented, of other assets which are owned but transferred to serve as collateral for the payment of the related debt obligation, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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