Earnings Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Mar. 18, 2013	May 23, 2011
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares		0.7
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Earnings Per Share Disclosure [Line Items]
Debt instrument, interest rate, stated percentage	1.50%	1.50%	1.50%	1.50%	2.50%
Performance Shares
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares		0.4
Maximum
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	0.1
Maximum | Performance Shares
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	0.1