Derivative Financial Instruments - Offsetting of Derivative Assets - Derivative Assets, Financial Assets, and Collateral Held by Counterparty (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Total
Net amounts of assets presented in the balance sheet	$ 232,948	$ 96,347
Net amount	232,948	96,347
Deutsche Bank AG
Total
Net amounts of assets presented in the balance sheet	8,187	26,770
Net amount	8,187	26,770
RJ O'Brien
Total
Net amounts of assets presented in the balance sheet	8,680	6,831
Net amount	8,680	6,831
Wells Fargo Bank, N.A.
Total
Net amounts of assets presented in the balance sheet	5,728	3,707
Net amount	5,728	3,707
Bank of America, N.A.
Total
Net amounts of assets presented in the balance sheet		2,781
Net amount		2,781
Citibank, N.A.
Total
Net amounts of assets presented in the balance sheet	15,951	2,488
Net amount	15,951	2,488
JP Morgan
Total
Net amounts of assets presented in the balance sheet	32,450	1,399
Net amount	32,450	1,399
Goldman Sachs
Total
Net amounts of assets presented in the balance sheet	2,252
Net amount	2,252
Morgan Stanley Bank
Total
Net amounts of assets presented in the balance sheet	11,842
Net amount	11,842
Other
Total
Net amounts of assets presented in the balance sheet	458	1,864
Net amount	458	1,864
Interest rate lock commitments
Total
Net amounts of assets presented in the balance sheet	147,400	50,507
Net amount	$ 147,400	$ 50,507