Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of activities related to unrecognized tax benefits
Balance at the beginning of the period	$ 12,344,000	$ 16,765,000
Additions to tax positions related to prior years	178,000	207,000
Subtractions to tax positions related to prior years	(395,000)	(1,720,000)
Subtractions to tax positions as a result of the lapse of the statute of limitations	0	(2,908,000)
Balance at the end of the period	12,127,000	12,344,000
Unrecognized tax benefits that, if recognized, would reduce annual effective tax rate	10,700,000	$ 10,600,000
Unrecognized tax benefits, interest accrued	0		$ 0	$ 0
Unrecognized tax benefits, penalties accrued	0		$ 0	$ 0
Expected decrease in unrecognized tax benefits during next fiscal year	$ 0