Investment Securities - (Summary of Available-for-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 1,036,935	$ 1,167,819
Gross unrealized gains	12,822	9,359
Gross unrealized losses	(3,710)	(19,932)
Investment securities available-for-sale (at fair value)	1,046,047	1,157,246
Residential Mortgage Pass-Through Securities Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	265,667	305,773
Gross unrealized gains	8,575	5,721
Gross unrealized losses		(516)
Investment securities available-for-sale (at fair value)	274,242	310,978
Other Residential MBS Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	765,669	861,321
Gross unrealized gains	4,235	3,638
Gross unrealized losses	(3,710)	(19,416)
Investment securities available-for-sale (at fair value)	766,194	845,543
Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	5,180
Gross unrealized gains	12
Investment securities available-for-sale (at fair value)	5,192
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	419	419
Investment securities available-for-sale (at fair value)	$ 419	$ 419

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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