Quarterly Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 1,777,961	$ 1,707,763	$ 1,686,345	$ 1,622,273	$ 1,694,600	$ 1,787,582	$ 1,758,628	$ 1,715,501	$ 6,794,342	$ 6,956,311	$ 7,752,728
Gross profit	619,704	631,788	631,213	589,264	613,809	672,608	654,568	627,159	2,471,969	2,568,144	2,974,249
Earnings from continuing operations	$ 161,162	$ 130,084	$ 118,290	$ 99,356	$ 136,574	$ 186,483	$ 155,634	$ 117,190	$ 508,892	$ 595,881	$ 778,140
Earnings from continuing operations (in dollars per basic share)	$ 1.04	$ 0.84	$ 0.76	$ 0.64	$ 0.88	$ 1.20	$ 0.98	$ 0.72	$ 3.28	$ 3.78	$ 4.67
Earnings from continuing operations (in dollars per diluted share)	$ 1.03	$ 0.83	$ 0.76	$ 0.64	$ 0.87	$ 1.19	$ 0.97	$ 0.72	$ 3.25	$ 3.74	$ 4.61
Net earnings	$ 161,162	$ 130,084	$ 118,290	$ 99,356	$ 141,825	$ 186,098	$ 332,396	$ 209,510	$ 508,892	$ 869,829	$ 775,235
Net earnings (in dollars per basic share)	$ 1.04	$ 0.84	$ 0.76	$ 0.64	$ 0.92	$ 1.20	$ 2.10	$ 1.30	$ 3.28	$ 5.52	$ 4.65
Net earnings (in dollars per diluted share)	$ 1.03	$ 0.83	$ 0.76	$ 0.64	$ 0.91	$ 1.19	$ 2.07	$ 1.28	$ 3.25	$ 5.46	$ 4.59