Income Taxes - Reconciliation of beginning and ending amount of unrecognized tax benefits (Details 3) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at January 1	$ 26,152,000	$ 23,267,000
Additions based on tax positions related to the current year	0	2,171,000
Additions for tax positions of prior years	0	714,000
Reductions for tax positions of prior years	(23,937,000)	0
Balance at December 31	$ 2,215,000	$ 26,152,000