11. Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Significant Noncash Transactions [Line Items]
Net Income (Loss) Attributable to Parent	$ 82,700	$ 22,100	$ 5,000	$ 12,400	$ (18,700)	$ 17,100	$ 16,600	$ 11,000	$ 122,249	$ 26,000	$ 109,239
Depreciation and amortization									148,700	142,900	131,800
Share-based compensation									23,400	19,700	17,000
Loss (gain) on disposition of securities									(100)	(800)	(1,600)
Other than Temporary Impairment Losses, Investments									7,000	600	600
Loss on disposition of fixed assets									8,100	600	300
Excess tax benefits from share-based compensation									0	(1,506)	(3,610)
Changes in fair value of contingent consideration									(18,100)	(400)	(5,600)
(Increase) decrease in accounts receivable, net									(64,100)	12,500	(39,000)
Increase in inventories, net									(47,700)	(57,100)	(54,200)
(Increase) decrease in Other Current Assets									(36,100)	(6,600)	100
Increase in accounts payable and other current liabilities									7,800	30,100	28,600
(Decrease) increase in Income Taxes Payable									(22,400)	10,700	12,700
Decrease in deferred income taxes									(82,000)	(51,400)	(4,000)
Other									5,200	5,700	4,300
Decrease in other long term assets									2,400	12,700	300
Increase (Decrease) in Other Long Term Liabilities									38,100	10,400	(10,700)
Impairment losses on goodwill and long-lived assets									11,506	62,305	0
Net cash provided by operating activities									103,885	216,433	186,210
Noncash or Part Noncash Acquisition, Fixed Assets Acquired									0	7,200	0
Noncash Purchased Marketable Securities and Investments									$ 2,800	$ 600	$ 2,200