Stockholders' Equity - Activities Under Equity Plan (Detail) - shares		3 Months Ended												12 Months Ended		39 Months Ended	43 Months Ended
	Jan. 02, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	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, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2015
Number of Shares Available for Grant [Roll Forward]
Beginning Balance, Equity securities available (shares)																	2,194,986
Granted (shares)		(6,242)	(5,494)	(4,823)	(5,328)	(7,110)	(6,006)	(5,093)	(6,475)	(6,266)	(4,606)	(4,712)	(5,350)			(67,505)
Ending Balance, Equity securities available (shares)														1,483,235		1,483,235	1,483,235
Common Stock
Number of Shares Available for Grant [Roll Forward]
Granted (shares)																	(5,820)
Non Executive Directors | Restricted Stock
Number of Shares Available for Grant [Roll Forward]
Forfeited (shares)																	3,189
Board Of Directors | Restricted Stock
Number of Shares Available for Grant [Roll Forward]
Granted (shares)																	(76,849)
2011 Long Term Incentive Plan | Restricted Stock Units
Number of Shares Available for Grant [Roll Forward]
Forfeited (shares)														18,432	57,338		209,382
Granted (shares)														(260,900)			(557,484)
Short Term Incentive Plan
Number of Shares Available for Grant [Roll Forward]
Granted (shares)																	(41,701)
2015 Long Term Incentive Plan | Restricted Stock Units
Number of Shares Available for Grant [Roll Forward]
Forfeited (shares)														18,432			18,432
Granted (shares)	(254,777)													(6,123)			(260,900)