Summary of Significant Accounting Policies - (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended							12 Months Ended
	Jan. 29, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Subsidiary, Sale of Stock [Line Items]
Number of shares issued	13,100,360		0	0	0	0	0	0		0	0
Deferred conversion costs		$ 4,100
Proceeds from initial public offering	$ 117,600
Capital contribution to subsidiary	$ 58,400
Employee Stock Ownership Plan (ESOP), percentage of shares to be purchased	8.00%
Employee Stock Ownership Plan (ESOP), number of shares to be purchased	1,048,029
Employee Stock Ownership Plan (ESOP), total shares									952,799
Employee Stock Ownership Plan (ESOP), percentage of shares purchased									90.90%
Employee Stock Ownership Plan (ESOP), number of allocated shares									17,510
Retained earnings					$ 79,663				$ 74,573	$ 79,663
Federal Reserve Bank, minimum reserve balance requirement					$ 4,200				7,400	$ 4,200
Contributions to charitable organization
Subsidiary, Sale of Stock [Line Items]
Value of charitable consideration, cash portion	$ 400								$ 400
Initial public offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued	12,167,000
Stock offering price per share (in usd per share)	$ 10.00
Secondary offering | Contributions to charitable organization
Subsidiary, Sale of Stock [Line Items]
Number of shares issued	933,360