Accounting Policies (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Other current assets	$ 118,423	$ 107,228	$ 108,220
Total current assets	712,298	653,180	654,172
Operating lease right-of-use assets	81,555	83,707	0
Total long-term assets	1,011,939	966,884	883,177
TOTAL ASSETS	1,724,237	1,620,064	1,537,349
LIABILITIES
Accrued liabilities	256,329	274,459	260,683
Total current liabilities	618,909	784,220	770,444
Long-term operating lease liabilities	69,331	68,939	0
Total long-term liabilities	933,779	845,077	776,138
TOTAL LIABILITIES	1,552,688	1,629,297	1,546,582
Lease obligation liabilities	84,334
Straight-line lease liabilities	79,352		84,826
Stranded tax effects	1,700
Accounting Standards Update 2016-02
ASSETS
Other current assets		(992)	1,000
Total current assets		(992)
Operating lease right-of-use assets	83,700	83,707
Total long-term assets		83,707
TOTAL ASSETS		82,715
LIABILITIES
Accrued liabilities		13,776
Total current liabilities		13,776
Long-term operating lease liabilities		68,939
Total long-term liabilities		68,939
TOTAL LIABILITIES		$ 82,715
Lease obligation liabilities	$ 86,700
Straight-line lease liabilities			$ 4,000