Annual report pursuant to Section 13 and 15(d)

Quarterly Financial Data -- Unaudited (Details)

v3.3.1.900
Quarterly Financial Data -- Unaudited (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]                      
Total revenue $ 1,196,146 $ 1,169,712 $ 1,123,210 $ 1,080,990 $ 1,090,952 $ 1,057,087 $ 1,035,345 $ 997,711 $ 4,570,058 $ 4,181,095 $ 3,799,095
Cost of services (470,523) (440,808) (525,463) (406,370) (421,098) (403,519) (393,185) (390,534)      
Income from operations 293,869 351,584 219,429 313,806 293,657 294,028 284,578 247,407 1,178,688 1,119,670 1,044,553
Net income $ 134,633 $ 166,550 $ 102,849 $ 105,692 $ 143,122 $ 136,170 $ 119,961 $ 93,988 $ 509,724 $ 493,241 $ 377,215
Net income per common share--basic (in dollars per share) $ 0.03 $ 0.03 $ 0.02 $ 0.02 $ 0.03 $ 0.02 $ 0.02 $ 0.02 $ 0.09 $ 0.09 $ 0.06
Net income per common share--diluted (in dollars per share) $ 0.03 $ 0.03 $ 0.02 $ 0.02 $ 0.03 [1] $ 0.02 [1] $ 0.02 [1] $ 0.02 [1] $ 0.09 $ 0.08 $ 0.06
[1] The sum of quarterly net income per share applicable to common stockholders (diluted) does not necessarily agree to the net income per share for the year due to the timing of common stock issuances