Stock repurchase program (Details) (USD $)	3 Months Ended		0 Months Ended	3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Mar. 18, 2013 Stock repurchase program announced on March 18, 2013	Sep. 30, 2013 Stock repurchase program announced on March 18, 2013
Stockholders Equity Note [Line Items]
Authorized amount for stock repurchases			$ 10,000,000
Payments for repurchase of common stock	3,132,000	2,985,000		3,100,000
Number of treasury shares acquired				538,835
Final price paid per share				$ 5.81
Stock Repurchase Program, Remaining Authorized Repurchase Amount				4,800,000
Reduction to common stock and APIC	1,700,000
Charge to retained earnings	$ 1,400,000