Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] | |||||||||||
Net income, Basic | $ 178,040 | $ 219,919 | $ 221,854 | ||||||||
Net income, Diluted | $ 178,040 | $ 219,919 | $ 221,854 | ||||||||
Weighted average common shares outstanding, Basic | 118,084 | 117,384 | 116,949 | ||||||||
Weighted average common shares outstanding, Basic | 118,084 | 117,384 | 116,949 | ||||||||
Weighted average shares and assumed conversions | 118,465 | 117,791 | 117,785 | ||||||||
BASIC EARNINGS PER SHARE | $ 0.35 | $ 0.35 | $ 0.38 | $ 0.42 | $ 0.52 | $ 0.47 | $ 0.49 | $ 0.39 | $ 1.51 | $ 1.87 | $ 1.90 |
DILUTED EARNINGS PER SHARE | $ 0.35 | $ 0.35 | $ 0.38 | $ 0.42 | $ 0.52 | $ 0.47 | $ 0.49 | $ 0.39 | $ 1.50 | $ 1.87 | $ 1.88 |
Stock options | |||||||||||
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] | |||||||||||
Effect of dilutive securities | 310 | 306 | 631 | ||||||||
Restricted stock based awards | |||||||||||
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] | |||||||||||
Effect of dilutive securities | 71 | 101 | 205 |