Organization and Significant Accounting Policies, Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Loss [Roll Forward]
Balance		$ 1,187,160	$ 365,280	$ 39,613
Net other comprehensive loss for the period		6,726	(257)	(1,401)
Balance		1,684,547	1,187,160	365,280
Income tax expense included in other comprehensive loss		1,400	300	0
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance		(32,016)	(31,759)	(30,358)
Balance		(25,290)	(32,016)	(31,759)
Unrealized Gains (Losses) on Securities [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Other comprehensive loss before reclassifications, net of tax	[1]	6,633	(280)	(960)
Amounts reclassified from accumulated other comprehensive loss		0	0	(374)
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Other comprehensive loss before reclassifications, net of tax		$ 93	$ 23	$ (67)

[1] A tax benefit of $1.4 million and $0.3 million was included in other comprehensive loss for the years ended December 31, 2019 and 2018, respectively. There was no tax benefit or expense for other comprehensive loss for the year ended December 31, 2017.