Share Based Compensation - Summarized Activity of Stock Option Awards (Detail) (Stock Options [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at beginning of year, Options Outstanding	2,006,000
Granted, Options Outstanding	0
Exercised, Options Outstanding	(56,000)
Forfeited, Options Outstanding	(89,000)
Balance at end of period, Options Outstanding	1,861,000	2,006,000
Exercisable at end of period, Options Outstanding	1,364,000
Balance at beginning of year, Weighted Average Exercise Price	$ 20.30
Granted, Weighted Average Exercise Price	$ 0.00
Exercised, Weighted Average Exercise Price	$ 9.64
Forfeited, Weighted Average Exercise Price	$ 17.65
Balance at end of period, Weighted Average Exercise Price	$ 20.74	$ 20.30
Exercisable at end of period, Weighted Average Exercise Price	$ 21.86
Weighted Average Remaining Contractual Term	6 years	7 years
Exercisable at end of period, Weighted Average Remaining Contractual Term	5 years
Aggregate intrinsic value	$ 643	$ 6,433
Exercisable at end of period, Aggregate Intrinsic Value	$ 620