Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Dec. 31, 2020	Jun. 01, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 900,204	$ 808,322	$ 900,204	$ 898,569		$ 808,322
Purchase accounting adjustments	1,635	0
Net intangible assets	81,364	$ 79,349	81,364	85,507
Remainder of fiscal year	15,900		15,900
2022	14,000		14,000
2023	12,300		12,300
2024	11,100		11,100
2025	$ 10,000		10,000
Min
Goodwill [Line Items]
Weighted average useful life	6 years
Max
Goodwill [Line Items]
Weighted average useful life	11 years
Core Deposits
Goodwill [Line Items]
Net intangible assets	$ 78,400		78,400	82,500
Customer Relationships
Goodwill [Line Items]
Net intangible assets	2,900		2,900	$ 3,000
Opus Bank
Goodwill [Line Items]
Goodwill					$ 91,882
Purchase accounting adjustments	$ 1,600		$ 962