Leases (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Operarting lease expense	$ 9,821,000	$ 13,500,000	$ 19,328,000	$ 27,000,000.0
Short-term lease expense	4,628,000		10,001,000
2019	30,800,000		30,800,000
2020	24,300,000		24,300,000
2021	16,600,000		16,600,000
2022	9,800,000		9,800,000
2023	6,900,000		6,900,000
Thereafter	$ 37,800,000		37,800,000
Accounting Standards Update 2016-02 [Member]
Effect of change in accounting principle			$ 100,000,000.0
Equity impact of adoption					$ 0