Noninterest Income - Gains and Losses on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Other Income and Expenses [Abstract]
Gains on exercises, net	$ 5,482	$ 9,927
Terminations	(415)	(922)
Changes in fair value, net	16,238	10,186
Gains on equity warrant assets, net	$ 21,305	$ 19,191

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

Name:	us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration