Equity and EPS - Reclassification out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	$ 3,775	$ 2,316	$ 3,570	$ 3,872	$ 3,527	$ 1,042	$ 4,599	$ 3,059	$ 13,533	$ 12,227	$ 2,265
Net income (loss) from continuing operations attributable to common shareholders									30,230	$ 25,318	$ 22,843
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss) from continuing operations attributable to common shareholders									28
Post Employment Benefit Items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service cost									(338)
Recognized net actuarial loss									269
Total before tax									(69)
Income tax expense (benefit)									90
Net income (loss) from continuing operations attributable to common shareholders									21
Equity Method Investment Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Foreign currency loss									13
Income tax expense (benefit)									(6)
Net income (loss) from continuing operations attributable to common shareholders									$ 7