CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Statement Of Financial Position [Abstract]
Securities held to maturity, estimated fair value	$ 592,151	$ 579,499
Loans receivable, unamortized yield adjustments	$ (59,183)	$ (66,567)
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	93,772,115	99,626,400
Common stock, shares outstanding	93,772,115	99,626,400
Employee Stock Ownership Plan (ESOP), Number of Suspense Shares	3,261,335	3,361,684