Earnings Per Share - Summary of Weighted Average Number of Common Shares Outstanding (Detail) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Denominator:
Basic common shares outstanding	45,652	45,651	45,598	45,205	45,026	44,963	44,681	44,242	45,538	44,731	44,332
Effect of dilutive stock options and restricted stock									1,468	1,400	919
Diluted common shares outstanding	47,097	47,051	46,990	46,841	46,712	46,424	45,929	45,449	47,006	46,131	45,251