Securities - Scheduled Contractual Maturities of HTM Debt Securities (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Amortized cost
Within One Year	$ 0
After One Year through Five Years	537,071
After Five Years through Ten Years	462,340
After Ten Years	1,938,839
Total	2,938,250
Fair value
Within One Year	0
After One Year through Five Years	492,046
After Five Years through Ten Years	391,013
After Ten Years	1,522,168
Total	$ 2,405,227
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	1.05%
After Five Years through Ten Years	1.83%
After Ten Years	1.79%
Total	1.66%
U.S. Treasury securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	532,294
After Five Years through Ten Years	0
After Ten Years	0
Total	532,294
Fair value
Within One Year	0
After One Year through Five Years	487,707
After Five Years through Ten Years	0
After Ten Years	0
Total	$ 487,707
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	1.05%
After Five Years through Ten Years	0.00%
After Ten Years	0.00%
Total	1.05%
U.S. government agency and U.S. government-sponsored enterprise debt securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	367,841
After Ten Years	635,253
Total	1,003,094
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	311,312
After Ten Years	491,583
Total	$ 802,895
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	1.89%
After Ten Years	1.90%
Total	1.90%
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	4,777
After Five Years through Ten Years	94,499
After Ten Years	1,115,265
Total	1,214,541
Fair value
Within One Year	0
After One Year through Five Years	4,339
After Five Years through Ten Years	79,701
After Ten Years	888,215
Total	$ 972,255
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	1.41%
After Five Years through Ten Years	1.61%
After Ten Years	1.70%
Total	1.69%
Municipal securities
Amortized cost
Within One Year	$ 0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	188,321
Total	188,321
Fair value
Within One Year	0
After One Year through Five Years	0
After Five Years through Ten Years	0
After Ten Years	142,370
Total	$ 142,370
Weighted Average Yield
Within One Year	0.00%
After One Year through Five Years	0.00%
After Five Years through Ten Years	0.00%
After Ten Years	2.00%
Total	2.00%