Computation of Basic and Diluted Earnings Per Share (Parenthetical) (Detail) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earnings Per Share [Abstract]
Denominator for basic earnings per common share - weighted average shares	95,935		95,848		95,745		95,383
Basic weighted-average common shares outstanding and non-vested restricted stock expected to vest	96,285		96,273		96,146		95,850
Percentage allocated to common shareholders	99.60%	[1]	99.60%	[1]	99.60%	[2]	99.50%	[2]

[1] (1) Basic weighted-average common shares outstanding 95,935 95,848 Basic weighted-average common shares outstanding and non-vested restricted stock expected to vest 96,285 96,273 Percentage allocated to common shareholders 99.6% 99.6%

[2] (1) Basic weighted-average common shares outstanding 95,745 95,383 Basic weighted-average common shares outstanding and non-vested restricted stock expected to vest 96,146 95,850 Percentage allocated to common shareholders 99.6% 99.5%