Earnings Per Share - Anti-dilutive Potential Shares of Common Stock Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	2,065	5,505	8,299
Interest rate (percent)			8.125%
3.00% Convertible Subordinated Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate (percent)	3.00%	3.00%	3.00%
4.75% Convertible Subordinated Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate (percent)	4.75%	4.75%	4.75%
Shares related to the potential conversion of convertible subordinated notes [Member] | 3.00% 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	0	861	3,613
Shares related to the potential conversion of convertible subordinated notes [Member] | 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	1,977	2,824	4,432
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	88	1,820	254