Fair Value - Assets and Liabilities Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets
Total available-for-sale securities, Fair value,	$ 8,428,032	$ 6,071,415
Collateralized Loan Obligations [Member]
Assets
Total available-for-sale securities, Fair value,	105,247
Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	8,428,032	6,071,415
Other assets	58,307	141,586
Liabilities
Other liabilities	(6,768)	(5,837)
Total
Net Assets (Liabilities)	8,479,571	6,207,164
Fair Value, Measurements, Recurring | Collateralized Loan Obligations [Member]
Assets
Total available-for-sale securities, Fair value,	105,247
Fair Value, Measurements, Recurring | Level 1
Assets
Other assets	7,382	11,691
Total
Net Assets (Liabilities)	7,382	11,691
Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	8,428,032	6,071,415
Other assets	50,925	129,895
Liabilities
Other liabilities	(1,238)	(1,283)
Total
Net Assets (Liabilities)	8,477,719	6,200,027
Fair Value, Measurements, Recurring | Level 2 | Collateralized Loan Obligations [Member]
Assets
Total available-for-sale securities, Fair value,	105,247
Fair Value, Measurements, Recurring | Level 3
Liabilities
Other liabilities	(5,530)	(4,554)
Total
Net Assets (Liabilities)	(5,530)	(4,554)
U.S. Treasury securities
Assets
Total available-for-sale securities, Fair value,	192,563	171,421
U.S. Treasury securities | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	192,563	171,421
U.S. Treasury securities | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	192,563	171,421
Residential - Government agency
Assets
Total available-for-sale securities, Fair value,	137,264	160,462
Residential - Government agency | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	137,264	160,462
Residential - Government agency | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	137,264	160,462
Residential - Government-sponsored enterprises
Assets
Total available-for-sale securities, Fair value,	1,491,100	447,200
Residential - Government-sponsored enterprises | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	1,491,100	447,200
Residential - Government-sponsored enterprises | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	1,491,100	447,200
Commercial - Government agency
Assets
Total available-for-sale securities, Fair value,	387,663	599,650
Commercial - Government agency | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	387,663	599,650
Commercial - Government agency | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	387,663	599,650
Commercial - Government-sponsored enterprises
Assets
Total available-for-sale securities, Fair value,	1,369,443	932,157
Commercial - Government-sponsored enterprises | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	1,369,443	932,157
Commercial - Government-sponsored enterprises | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	1,369,443	932,157
Government agency
Assets
Total available-for-sale securities, Fair value,	2,079,523	1,933,553
Government agency | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	2,079,523	1,933,553
Government agency | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	2,079,523	1,933,553
Government-sponsored enterprises
Assets
Total available-for-sale securities, Fair value,	2,621,044	1,826,972
Government-sponsored enterprises | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	2,621,044	1,826,972
Government-sponsored enterprises | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	2,621,044	$ 1,826,972
Debt securities issued by states and political subdivisions
Assets
Total available-for-sale securities, Fair value,	44,185
Debt securities issued by states and political subdivisions | Fair Value, Measurements, Recurring
Assets
Total available-for-sale securities, Fair value,	44,185
Debt securities issued by states and political subdivisions | Fair Value, Measurements, Recurring | Level 2
Assets
Total available-for-sale securities, Fair value,	$ 44,185