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Earnings Per Share - (Additional Information) (Detail) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 22, 2019	Sep. 23, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jul. 31, 2019	Jul. 19, 2019	Jul. 16, 2019	Dec. 31, 2018
Stock options, outstanding			959,916		959,916					998,226
Stock options, weighted average exercise price			$ 30.44		$ 30.44					$ 27.54
Common stock excluded from calculation of diluted earnings per share			47,705	329,409	85,503	485,520
Common Stock [Member]
Conversion of Convertible Securities Stock Issued			2,316,200
2.125% Convertible Senior Notes due 2021
Aggregate principal amount			$ 115,000,000.0		$ 115,000,000.0				$ 92,000,000.0
2.125% Convertible Senior Notes due 2021 \| Common Stock [Member]
Conversion of Convertible Securities Stock Issued	1,850,155	466,045
0.375% Convertible Senior Notes due 2024
Aggregate principal amount							$ 287,500,000	$ 287,500,000
Option To Purchase Common Stock [Member]
Stock options, outstanding			959,916	1,033,312	959,916	1,033,312
Stock options, weighted average exercise price			$ 30.44	$ 26.99	$ 30.44	$ 26.99
Restricted Stock Units (RSUs) [Member]
Restricted stock units, outstanding			740,213	707,716	740,213	707,716				707,413