Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Letters of credit outstanding	$ 226,900	$ 219,100
Surety bonds outstanding	$ 1,100,000	1,100,000
Maximum product warranty in years	10 years
Self-insurance liabilities	$ 835,300	831,058	$ 922,385	$ 924,563
Incurred but not reported percentage of liability reserves	70.00%
Write-off of insurance receivables	15.0
litigation of recorded insurance receivable	$ 99,300
Other Assets
Loss Contingencies [Line Items]
Recorded insurance receivables	$ 291,800	$ 307,300