Annual report pursuant to Section 13 and 15(d)

Quarterly Financial Information (Summary Of Quarterly Financial Information) (Details)

v3.8.0.1
Quarterly Financial Information (Summary Of Quarterly Financial Information) (Details) - USD ($)
$ / shares in Units, $ 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
Selected Quarterly Financial Information [Abstract]                      
Revenue $ 891,117 $ 872,987 $ 839,912 $ 754,096 $ 745,738 $ 782,611 $ 755,435 $ 707,733 $ 3,358,112 $ 2,991,517 $ 2,972,442
Operating income 143,457 163,875 160,432 108,122 113,447 137,404 133,436 99,548 575,886 483,835 498,240
Net income $ 197,250 $ 102,314 $ 98,418 $ 65,792 $ 68,511 $ 85,581 $ 81,388 $ 60,285 $ 463,774 $ 295,765 $ 304,690
Earnings Per Share, Basic $ 2.40 $ 1.24 $ 1.20 $ 0.80 $ 0.83 $ 1.03 $ 0.98 $ 0.72 $ 5.63 $ 3.56 $ 3.57
Earnings Per Share, Diluted $ 2.39 $ 1.24 $ 1.19 $ 0.80 $ 0.83 $ 1.03 $ 0.98 $ 0.72 $ 5.63 $ 3.56 $ 3.57