Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2019 shares	Jun. 30, 2019 shares	Dec. 31, 2019 USD ($) vote / shares $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 shares	Mar. 31, 2016 USD ($)
Common Stock And Preferred Stock [Line Items]
Common stock, shares authorized | shares			190,000,000	190,000,000
Common stock, par value | $ / shares			$ 0.001	$ 0.001
Common stock, shares issued | shares			18,908,566	19,620,546
Common stock, shares outstanding | shares			16,842,757	17,554,737
Common stock, number of vote per share | vote / shares			1
Stock Repurchase Program, Authorized Amount							$ 125,000
Payments for Repurchase of Common Stock			$ (36,550)	$ (59,955)	$ (55,123)
Treasury Stock, Value, Acquired, Cost Method			35,937	$ 60,566	$ 55,947
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 98,720
Open Market [Member]
Common Stock And Preferred Stock [Line Items]
Treasury Stock, Shares, Acquired | shares			85,000	324,508
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 69.85	$ 78.78
Treasury Stock, Value, Acquired, Cost Method			$ 5,937	$ 25,565
ASR [Member]
Common Stock And Preferred Stock [Line Items]
Treasury Stock, Shares, Acquired | shares	72,875	626,305	699,180	258,285
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 42.91	$ 135.51
Treasury Stock, Value, Acquired, Cost Method			$ 30,000	$ 35,000
Common Stock [Member]
Common Stock And Preferred Stock [Line Items]
Common stock, shares outstanding | shares			16,842,757	17,554,737	17,914,599	17,690,611
Treasury Stock, Shares, Acquired | shares			817,954	549,019	513,801
Treasury Stock, Value, Acquired, Cost Method			$ 0	$ 1	$ 1
2018 Program [Member]
Common Stock And Preferred Stock [Line Items]
Stock Repurchase Program, Authorized Amount			$ 150,000