Acquisitions - Pro Forma Information (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
Business Acquisition, Pro Forma Information [Abstract]
Acquisition related costs (after tax)									$ 1,999
Amount of nonrecurring expense, excluded from current period net earnings in pro forma financials, related to the fair value adjustments to acquisition-date inventory									2,560
Revenue from continuing operations [Abstract]
As reported	$ 1,694,600	$ 1,787,582	$ 1,758,628	$ 1,715,501	$ 1,977,947	$ 2,009,575	$ 1,962,636	$ 1,802,570	6,956,311	$ 7,752,728	$ 7,155,096
Pro forma									7,096,102	8,148,820
Earnings from continuing operations [Abstract]
As reported	$ 136,574	$ 186,483	$ 155,634	$ 117,190	$ 171,835	$ 225,683	$ 210,581	$ 170,041	595,881	778,140	$ 797,527
Pro forma									$ 623,350	$ 795,754
Basic earnings per share from continuing operations [Abstract]
As reported (in dollars per share)	$ 0.88	$ 1.20	$ 0.98	$ 0.72	$ 1.04	$ 1.36	$ 1.26	$ 1.00	$ 3.78	$ 4.67	$ 4.66
Pro forma (in dollars per share)									3.95	4.77
Diluted earnings per share from continuing operations [Abstract]
As reported (in dollars per share)	$ 0.87	$ 1.19	$ 0.97	$ 0.72	$ 1.03	$ 1.34	$ 1.25	$ 0.99	3.74	4.61	$ 4.60
Pro forma (in dollars per share)									$ 3.92	$ 4.71