Securities Available for Sale - Stratification by Contractual Maturity of Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Investments Debt And Equity Securities [Abstract]
Due after one year through five years, Amortized Cost	$ 153,819
Due after five years through ten years, Amortized Cost	46,216
Due after ten years, Amortized Cost	348,319
Securities available for sale, Amortized Cost	548,354
Due after one year through five years, Fair Value	150,554
Due after five years through ten years, Fair Value	45,375
Due after ten years, Fair Value	347,903
Fair Value	$ 543,832	$ 590,562

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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