Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jan. 26, 2017	Apr. 30, 2010	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2000
Stockholders Equity Note [Line Items]
Number of shares authorized to be repurchased			86,500,000
Remaining authorized repurchase amount			7,463,000
Cash dividends declared, per share			$ 2.20	$ 2.12	$ 1.92
Total number of shares repurchased and retired			2,908,000	2,179,000	554,000
Total investment			$ 245,816	$ 293,616	$ 81,812
Employee Stock Purchase Plan Number Of Shares Available For Issuance			3,000,000
Share Based Compensation Arrangements By Share Based Payment Award Percentage Of Market Price At Eligible Employees Granted Options To Purchase Shares			95.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans			1,324,000
Common stock excluded from calculation of diluted earnings per share			2,463,000	1,001,000	581,000
Stockholder Rights Plan [Member]
Stockholders Equity Note [Line Items]
Minimum Percentage Of Ownership Acquired Or To Be Acquired Upon Which Purchase Rights Become Exercisable						15.00%
Common Stock Dividends Right Per Share Declared						1
Dividends Payable, Date of Record						Jun. 01, 2000
Incentive Stock Purchase Rights Redemption Price Per Right		$ 0.01
Stockholder Rights Plan [Member] | Maximum
Stockholders Equity Note [Line Items]
Common Stock Price Per Share Under Rights Plan		125
Stockholder Rights Plan [Member] | Minimum
Stockholders Equity Note [Line Items]
Common Stock Price Per Share Under Rights Plan		$ 75
Subsequent Event
Stockholders Equity Note [Line Items]
Cash dividends declared, per share	$ 0.58