Derivatives - Schedule of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jul. 31, 2017
Derivatives Fair Value [Line Items]
Notional amount			$ 100,000
Not Designated As Hedging
Derivatives Fair Value [Line Items]
Notional amount	$ 1,789,798	$ 1,810,484
Asset	13,821	8,258
Liability	5,480	1,699
Not Designated As Hedging | Interest rate contracts
Derivatives Fair Value [Line Items]
Notional amount	231,899	146,754
Asset	3,798	1,146
Liability	3,798	1,146
Not Designated As Hedging | Forward commitments
Derivatives Fair Value [Line Items]
Notional amount	717,330	870,574
Liability	1,682	553
Not Designated As Hedging | Interest rate-lock commitments
Derivatives Fair Value [Line Items]
Notional amount	597,569	504,156
Asset	9,495	6,768
Not Designated As Hedging | Futures Contracts
Derivatives Fair Value [Line Items]
Notional amount	231,000	283,000
Asset	445	315
Not Designated As Hedging | Option Contracts
Derivatives Fair Value [Line Items]
Notional amount	12,000	6,000
Asset	83	29
Designated as Hedging
Derivatives Fair Value [Line Items]
Notional amount	30,000	130,000
Asset	1,296	1,432
Designated as Hedging | Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional amount	30,000	130,000
Asset	$ 1,296	$ 1,432