Earnings Per Share - Anti-dilutive Potential Shares of Common Stock Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potential shares of common stock excluded from computation of earnings per share, amount	4	1,634	52	1,798
Common stock related to employee equity awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potential shares of common stock excluded from computation of earnings per share, amount	4	7	52	3
4.75% Convertible Subordinated Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potential shares of common stock excluded from computation of earnings per share, amount	0	1,627	0	1,795
Interest rate (percent)		4.75%		4.75%