Income Taxes - Reconciliation of Unrecognized Income Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 841,000	$ 3,982,000
Additions based on tax positions related to the current year	0	1,158,000
Additions based on tax positions related to prior years	0	1,244,000
Adjustments for tax positions of prior years	184,000
Adjustments for tax positions of prior years		(5,543,000)
Reductions for expired statute of limitations	(1,025,000)	0
Balance at end of year	$ 0	$ 841,000