Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period			$ 765,842
Total goodwill, end of period	$ 765,842	$ 765,842	765,842	$ 765,842
CDI current period amortization	(1,852)	(2,210)	(3,776)	(4,520)
Indefinite-lived Intangible Assets (Excluding Goodwill)	919	919	919	919
Other intangible assets, net	22,958	30,938	22,958	30,938		$ 26,734
Total goodwill and intangible assets, end of period	788,800	796,780	788,800	796,780
Core Deposits [Member]
Goodwill and Intangible Assets [Roll Forward]
Gross core deposit intangible balance, beginning of period					$ 105,473	105,473	$ 105,473	$ 105,473
Accumulated amortization at beginning of period					$ (81,582)	$ (79,658)	$ (73,244)	$ (70,934)
Core deposit intangible, net, beginning of period	23,891	32,229	25,815	34,539
CDI current period amortization	(1,852)	(2,210)	(3,776)	(4,520)
Total core deposit intangible, end of period	$ 22,039	$ 30,019	$ 22,039	$ 30,019