Noninterest Income - Gains on Investment Securities, Net (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gains and Losses on Investments [Abstract]
Gains on non-marketable and other equity securities, net	$ 88,834	$ 69,792	$ 39,545
(Losses) gains on sales of available-for-sale debt securities, net	(740)	(5,189)	12,195
Gains on investment securities, net	$ 88,094	$ 64,603	$ 51,740

Amount of realized and unrealized gain (loss) on investment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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