Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial assets:
Securities available for sale, at fair value	$ 2,163,820	$ 1,343,457
Derivative instruments	10,643	3,866
Financial liabilities:
Derivative instruments	16,705	21,107
Trust preferred securities
Financial assets:
Securities available for sale, at fair value		9,012
Recurring
Financial assets:
Securities available for sale, at fair value		1,343,457
Derivative instruments	27,470	33,574
Mortgage loans held for sale in loans held for sale	448,959	417,771
Total financial assets	2,640,249	1,794,802
Financial liabilities:
Derivative instruments	16,804	21,107
Recurring \| Securities available for sale
Financial assets:
Securities available for sale, at fair value	2,163,820	1,334,445
Recurring \| Trust preferred securities
Financial assets:
Securities available for sale, at fair value		9,012
Recurring \| Level 1
Financial assets:
Securities available for sale, at fair value		0
Derivative instruments	0	0
Mortgage loans held for sale in loans held for sale	0	0
Total financial assets	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring \| Level 1 \| Securities available for sale
Financial assets:
Securities available for sale, at fair value	0	0
Recurring \| Level 1 \| Trust preferred securities
Financial assets:
Securities available for sale, at fair value		0
Recurring \| Level 2
Financial assets:
Securities available for sale, at fair value		1,334,445
Derivative instruments	27,470	33,574
Mortgage loans held for sale in loans held for sale	448,959	417,771
Total financial assets	2,640,249	1,785,790
Financial liabilities:
Derivative instruments	16,804	21,107
Recurring \| Level 2 \| Securities available for sale
Financial assets:
Securities available for sale, at fair value	2,163,820	1,334,445
Recurring \| Level 2 \| Trust preferred securities
Financial assets:
Securities available for sale, at fair value		0
Recurring \| Level 3
Financial assets:
Securities available for sale, at fair value		9,012
Derivative instruments	0	0
Mortgage loans held for sale in loans held for sale	0	0
Total financial assets	0	9,012
Financial liabilities:
Derivative instruments	0	0
Recurring \| Level 3 \| Securities available for sale
Financial assets:
Securities available for sale, at fair value	$ 0	0
Recurring \| Level 3 \| Trust preferred securities
Financial assets:
Securities available for sale, at fair value		$ 9,012

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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