Impairment of Securities - Schedule of Fair Values and Gross Unrealized and Unrecognized Losses on Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	$ 290,216	$ 293,729
Less than 12 Months: Unrealized Losses	4,746	3,755
12 Months or More: Fair Value	213,413	144,404
12 Months or More: Unrealized Losses	5,165	3,970
Total: Fair Value	503,629	438,133
Total: Unrealized Losses	9,911	7,725
Debt Securities [Member] | Trust Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or More: Fair Value	2,726	2,783
12 Months or More: Unrealized Losses	241	184
Total: Fair Value	2,726	2,783
Total: Unrealized Losses	241	184
Debt Securities [Member] | U.S. Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	765	2,579
Less than 12 Months: Unrealized Losses	3	43
12 Months or More: Fair Value	3,177	1,832
12 Months or More: Unrealized Losses	48	20
Total: Fair Value	3,942	4,411
Total: Unrealized Losses	51	63
Debt Securities [Member] | Obligations of State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	3,145	24,443
Less than 12 Months: Unrealized Losses	14	672
12 Months or More: Fair Value	21,744	540
12 Months or More: Unrealized Losses	566	37
Total: Fair Value	24,889	24,983
Total: Unrealized Losses	580	709
Debt Securities [Member] | Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	53,235
Less than 12 Months: Unrealized Losses	168
12 Months or More: Fair Value	14,942	24,728
12 Months or More: Unrealized Losses	30	134
Total: Fair Value	68,177	24,728
Total: Unrealized Losses	198	134
Debt Securities [Member] | Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	162,821	189,258
Less than 12 Months: Unrealized Losses	1,773	914
12 Months or More: Fair Value	14,862
12 Months or More: Unrealized Losses	168
Total: Fair Value	177,683	189,258
Total: Unrealized Losses	1,941	914
Debt Securities [Member] | Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	70,236	5,035
Less than 12 Months: Unrealized Losses	2,788	4
12 Months or More: Fair Value	44,383	64,184
12 Months or More: Unrealized Losses	594	790
Total: Fair Value	114,619	69,219
Total: Unrealized Losses	3,382	794
Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value		4,635
Less than 12 Months: Unrealized Losses		135
12 Months or More: Fair Value	23,019	19,658
12 Months or More: Unrealized Losses	940	1,224
Total: Fair Value	23,019	24,293
Total: Unrealized Losses	940	1,359
Residential Pass-Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value	14	63,889
Less than 12 Months: Unrealized Losses		1,921
12 Months or More: Fair Value	80,727	26,697
12 Months or More: Unrealized Losses	2,548	1,573
Total: Fair Value	80,741	90,586
Total: Unrealized Losses	2,548	3,494
Commercial Pass-Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months: Fair Value		3,890
Less than 12 Months: Unrealized Losses		66
12 Months or More: Fair Value	7,833	3,982
12 Months or More: Unrealized Losses	30	8
Total: Fair Value	7,833	7,872
Total: Unrealized Losses	$ 30	$ 74