Noninterest Income - Gains and Losses on Investments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Other Income and Expenses [Abstract]
Total net gains on non-marketable and other equity securities	$ 32,658	$ 9,058
Losses on sales of available-for-sale securities, net	(3,630)	0
Gains on investment securities, net	$ 29,028	$ 9,058

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
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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