Derivatives - Schedule of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Jul. 31, 2017
Derivatives, Fair Value [Line Items]
Notional Amount			$ 100,000
Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	$ 2,201,716	$ 1,258,047
Asset	29,172	13,595
Liability	19,050	11,637
Interest rate contracts | Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	427,468	295,333
Asset	19,050	6,679
Liability	19,050	6,679
Forward commitments | Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	824,724	474,208
Asset	582	0
Liability	0	4,958
Interest rate-lock commitments | Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	679,524	318,706
Asset	9,142	6,241
Liability	0	0
Futures contracts | Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	270,000	166,000
Asset	398	649
Liability	0	0
Option contracts | Not designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	0	3,800
Asset	0	26
Liability	0	0
Interest rate swaps | Designated as hedging:
Derivatives, Fair Value [Line Items]
Notional Amount	30,000	30,000
Asset	0	721
Liability	$ 837	$ 0