Borrowings (Repurchase Agreements) (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Borrowing Balance	$ 552,266	$ 328,748
Securities Sold under Agreements to Repurchase [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 387,379	$ 192,500
Weighted Average Coupon	2.20%
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 07 03 2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 60,000
Weighted Average Coupon	2.26%
Settlement Date	Jun. 08, 2018
Investment Repurchase Agreement, Repurchase Date	Jul. 03, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date: 7/3/2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 46,427
Weighted Average Coupon	2.32%
Settlement Date	Jun. 26, 2018
Investment Repurchase Agreement, Repurchase Date	Jul. 03, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date 07 12 2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 28,522
Weighted Average Coupon	2.16%
Settlement Date	Jun. 15, 2018
Investment Repurchase Agreement, Repurchase Date	Jul. 12, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date 07 20 2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 49,970
Weighted Average Coupon	2.22%
Settlement Date	Jun. 22, 2018
Investment Repurchase Agreement, Repurchase Date	Jul. 20, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date 07 25 2018 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 12,460
Weighted Average Coupon	2.18%
Settlement Date	Jun. 25, 2018
Investment Repurchase Agreement, Repurchase Date	Jul. 25, 2018
Securities Sold under Agreements to Repurchase [Member] \| Due date: 09 03 2019 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 50,000
Weighted Average Coupon	1.72%
Settlement Date	Mar. 02, 2017
Investment Repurchase Agreement, Repurchase Date	Sep. 03, 2019
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 3/2/2020 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 60,000
Weighted Average Coupon	1.85%
Settlement Date	Mar. 02, 2017
Investment Repurchase Agreement, Repurchase Date	Mar. 02, 2020
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 3/15/2020 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 50,000
Weighted Average Coupon	2.61%
Settlement Date	Mar. 15, 2018
Investment Repurchase Agreement, Repurchase Date	Mar. 15, 2020
Securities Sold under Agreements to Repurchase [Member] \| Due Date: 3/23/2020 [Member]
Debt Instrument [Line Items]
Borrowing Balance	$ 30,000
Weighted Average Coupon	2.70%
Settlement Date	Mar. 23, 2018
Investment Repurchase Agreement, Repurchase Date	Mar. 23, 2020

Date the repurchase agreement was made.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Footnote 2

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Date the repurchase will be made.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Footnote 2

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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.

+ References

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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