Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Contingencies [Abstract]
Rent expense	$ 44,900	$ 40,200	$ 38,400
Future mimimum property lease commitments [Abstract]
2017	53,800
2018	41,000
2019	32,400
2020	28,700
2021	24,900
Thereafter	51,600
Total future minimum property lease commitments	232,400
Product Warranty Disclosure [Abstract]
Balance at beginning of year	10,183	9,537	14,336
Additions charged to costs and expenses	15,950	14,284	13,396
Deductions	(15,513)	(13,059)	(18,078)
Other	(72)	(579)	(117)
Balance at end of year	10,548	$ 10,183	$ 9,537
Outstanding surety bonds	$ 521,000