Components of Calculation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[2]	Sep. 30, 2016	[2]	Jun. 30, 2016	[2]	Mar. 31, 2016	[2]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 146,119		$ 72,382		$ 27,926		$ 23,232		$ 23,694		$ 69,770		$ 33,315		$ 26,572		$ 269,659	$ 153,351	$ 172,413
Weighted average number of shares used in:
Basic earnings per share																	110,353	119,732	122,042
Dilutive common stock equivalents:
Restricted stock units																	1,010	766	570
Diluted earnings per share																	111,363	120,498	122,612

[1] The first, second, third and fourth quarters of 2017 include rationalization charges of $0.9 million, $3.0 million, $0.6 million and $1.3 million, respectively. The first, second, third and fourth quarters of 2017 includes costs attributed to announced acquisitions of $13.2 million, $9.8 million, $0.8 million and $0.9 million, respectively. The first and second quarters of 2017 include a loss on early extinguishment of debt of $2.7 million and $4.4 million, respectively. The fourth quarter of 2017 includes the benefit from effective tax rate adjustments totaling $110.9 million primarily related to the remeasurement of net deferred tax liabilities to reflect the lower future cash tax obligations as a result of the reduction in the federal corporate tax rate under the 2017 Tax Act.

[2] The first, second, third and fourth quarters of 2016 include rationalization charges of $1.1 million, $5.0 million, $7.8 million and $5.1 million, respectively. The fourth quarter of 2016 includes costs attributed to announced acquisitions of $1.4 million.