Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
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	(2,210)	(2,649)	(4,520)	(5,397)
Indefinite-lived Intangible Assets (Excluding Goodwill)	919	919	919	919
Other intangible assets, net	30,938	40,540	30,938	40,540		$ 35,458
Total goodwill and intangible assets, end of period	796,780	806,382	$ 796,780	806,382
Core Deposits [Member]
Goodwill and Intangible Assets [Line Items]
Estimated life of CDI, in years			10 years
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					$ (73,244)	$ (70,934)	$ (63,203)	$ (60,455)
Core deposit intangible, net, beginning of period	32,229	42,270	$ 34,539	45,018
CDI current period amortization	(2,210)	(2,649)	(4,520)	(5,397)
Total core deposit intangible, end of period	$ 30,019	$ 39,621	$ 30,019	$ 39,621