Fair Value of Financial Instruments - Schedule of Fair Value, by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016
Carrying Value | Cash and interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 86,985	$ 52,596
Carrying Value | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	149,863	229,859
Carrying Value | Certificates of deposit in other banks
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	132,274	161,512
Carrying Value | Securities available for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	199,667	200,652
Carrying Value | Loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	2,330,319	1,811,539
Carrying Value | Loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	5,607	5,783
Carrying Value | FHLB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	32,071	23,304
Carrying Value | FRB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	7,284	6,182
Carrying Value | Accrued interest receivable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	8,758	7,405
Carrying Value | Noninterest-bearing and NOW deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	779,549	628,910
Carrying Value | Money market accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	569,607	520,320
Carrying Value | Savings accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	237,149	210,817
Carrying Value | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	462,146	442,649
Carrying Value | Borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	696,500	491,000
Carrying Value | Accrued interest payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	512	246
Estimate of Fair Value Measurement [Member] | Cash and interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	86,985	52,596
Estimate of Fair Value Measurement [Member] | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	149,863	229,859
Estimate of Fair Value Measurement [Member] | Certificates of deposit in other banks
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	132,274	161,512
Estimate of Fair Value Measurement [Member] | Securities available for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	199,667	200,652
Estimate of Fair Value Measurement [Member] | Loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	2,230,683	1,761,926
Estimate of Fair Value Measurement [Member] | Loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	5,719	5,876
Estimate of Fair Value Measurement [Member] | FHLB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	32,071	23,304
Estimate of Fair Value Measurement [Member] | FRB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	7,284	6,182
Estimate of Fair Value Measurement [Member] | Accrued interest receivable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	8,758	7,405
Estimate of Fair Value Measurement [Member] | Noninterest-bearing and NOW deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	779,549	628,910
Estimate of Fair Value Measurement [Member] | Money market accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	569,607	520,320
Estimate of Fair Value Measurement [Member] | Savings accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	237,149	210,817
Estimate of Fair Value Measurement [Member] | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	458,818	442,203
Estimate of Fair Value Measurement [Member] | Borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	696,500	491,000
Estimate of Fair Value Measurement [Member] | Accrued interest payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	512	246
Estimate of Fair Value Measurement [Member] | Level 1 | Cash and interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	86,985	52,596
Estimate of Fair Value Measurement [Member] | Level 1 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	149,863	229,859
Estimate of Fair Value Measurement [Member] | Level 1 | FHLB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	32,071	23,304
Estimate of Fair Value Measurement [Member] | Level 1 | FRB stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	7,284	6,182
Estimate of Fair Value Measurement [Member] | Level 1 | Accrued interest receivable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	331	271
Estimate of Fair Value Measurement [Member] | Level 2 | Certificates of deposit in other banks
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	132,274	161,512
Estimate of Fair Value Measurement [Member] | Level 2 | Securities available for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	199,667	199,652
Estimate of Fair Value Measurement [Member] | Level 2 | Accrued interest receivable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	1,078	835
Estimate of Fair Value Measurement [Member] | Level 2 | Noninterest-bearing and NOW deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	779,549	628,910
Estimate of Fair Value Measurement [Member] | Level 2 | Money market accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	569,607	520,320
Estimate of Fair Value Measurement [Member] | Level 2 | Savings accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	237,149	210,817
Estimate of Fair Value Measurement [Member] | Level 2 | Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	458,818	442,203
Estimate of Fair Value Measurement [Member] | Level 2 | Borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	696,500	491,000
Estimate of Fair Value Measurement [Member] | Level 2 | Accrued interest payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	512	246
Estimate of Fair Value Measurement [Member] | Level 3 | Securities available for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	0	1,000
Estimate of Fair Value Measurement [Member] | Level 3 | Loans, net
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	2,230,683	1,761,926
Estimate of Fair Value Measurement [Member] | Level 3 | Loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	5,719	5,876
Estimate of Fair Value Measurement [Member] | Level 3 | Accrued interest receivable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 7,349	$ 6,299