Annual report pursuant to Section 13 and 15(d)

UNAUDITED QUARTERLY DATA (Details)

v3.10.0.1
UNAUDITED QUARTERLY DATA (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
UNAUDITED QUARTERLY DATA                      
Revenues $ 444,623 $ 487,739 $ 480,461 $ 408,742 $ 414,713 $ 450,442 $ 433,555 $ 375,247 $ 1,821,565 $ 1,673,957 $ 1,573,477
Gross profit (Revenues less cost of services provided) 223,389 251,452 249,689 202,599 207,194 231,661 229,075 186,084      
Net Income $ 50,968 $ 66,628 $ 65,542 $ 48,525 $ 33,735 $ 51,430 $ 53,689 $ 40,270 $ 231,663 $ 179,124 $ 167,369
Income per share:                      
Income per share - Basic (in dollars per share) $ 0.16 $ 0.20 $ 0.20 $ 0.15 $ 0.10 $ 0.16 $ 0.17 $ 0.12 $ 0.71 $ 0.55 $ 0.51
Income per share - Diluted (in dollars per share) $ 0.16 $ 0.20 $ 0.20 $ 0.15 $ 0.10 $ 0.16 $ 0.17 $ 0.12 $ 0.71 $ 0.55 $ 0.51