Earnings per Share Data (Detail) - Basic Earnings Per Share - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Basic weighted-average shares (in shares)	23,167	22,835	23,079	22,764
Conversion of unsecured loan notes (in shares)	0	7	0	0
Unexercised options and unvested RSUs (in shares)	0	374	0	0
Diluted weighted-average shares (in shares)	23,167	23,216	23,079	22,764