Share-Based Payment Arrangements - Schedule of Option Activity Under Stock Option Plans (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding at Beginning	1,332,656
Number of Shares, Exercised	(29,281)
Number of Shares, Forfeited	(13,680)
Number of Shares, Expired	(113,447)
Number of Shares, Outstanding at Ending	1,176,248
Number of Shares, Exercisable at Ending	891,217
Weighted- Average Exercise Price, Outstanding at Beginning	$ 38.85
Weighted- Average Exercise Price, Exercised	$ 29.35
Weighted- Average Exercise Price, Forfeited	$ 38.27
Weighted- Average Exercise Price, Expired	$ 63.41
Weighted- Average Exercise Price, Outstanding at Ending	$ 36.72
Weighted- Average Exercise Price, Exercisable at Ending	$ 38.52
Weighted-Average Remaining Contractual Term, Outstanding at Ending Balance (in years)	4 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable at Ending Balance (in years)	3 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding at Ending	$ 2,770
Aggregate Intrinsic Value, Exercisable at Ending	$ 1,494