Acquisitions - Pro Forma Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition, Pro Forma Information [Abstract]
Acquisition related costs (after tax)									$ 3,502
Amount of nonrecurring expense, excluded from current period net earnings in pro forma financials, related to the fair value adjustments to acquisition-date inventory									11,558
Revenue from continuing operations [Abstract]
As reported	1,977,947	2,009,575	1,962,636	1,802,570	1,785,922	1,850,653	1,836,981	1,681,540	7,752,728	7,155,096	6,626,648
Pro forma									7,987,639	7,602,756
Earnings from continuing operations [Abstract]
As reported	171,835	225,683	210,581	170,041	172,227	217,045	247,988	160,267	778,140	797,527	650,075
Pro forma									$ 806,321	$ 794,823
Basic earnings per share from continuing operations [Abstract]
As reported (in dollars per share)	$ 1.04	$ 1.36	$ 1.26	$ 1.00	$ 1.01	$ 1.27	$ 1.45	$ 0.92	$ 4.67	$ 4.66	$ 3.58
Pro forma (in dollars per share)									$ 4.84	$ 4.64
Diluted earnings per share from continuing operations [Abstract]
As reported (in dollars per share)	$ 1.03	$ 1.34	$ 1.25	$ 0.99	$ 1.00	$ 1.26	$ 1.43	$ 0.91	$ 4.61	$ 4.60	$ 3.53
Pro forma (in dollars per share)									$ 4.78	$ 4.58