Schedule II - Valuation and Qualifying Acconts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 161	$ 166	$ 202	$ 177
Addition charged to costs and expenses	0	0	25
Other additions (deductions)	(5)	(36)	0
Less deductions	0	0	0
Balance at end of year	166	202		177
Deferred tax asset valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	72,104	65,832	56,574	63,931
Addition charged to costs and expenses	0	0	0
Other additions (deductions)	6,272	9,258	(7,357)
Less deductions	0	0	0
Balance at end of year	$ 65,832	$ 56,574		$ 63,931