Accumulated Other Comprehensive Loss (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period			$ 651,983,000
Other comprehensive income before reclassifications	$ 361,000	$ (37,000)	33,000	$ 278,000
Amounts reclassified from accumulated other comprehensive income			0	(9,665,000)
Other comprehensive income (loss)	361,000	(37,000)	33,000	(9,387,000)
Balance at end of period	142,953,000		142,953,000
Unrealized gains and losses on available-for-sale securities, tax impact			0	0
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	(5,807,000)	(5,377,000)	(5,479,000)	3,973,000
Balance at end of period	(5,446,000)	(5,414,000)	(5,446,000)	(5,414,000)
Foreign currency translation adjustment
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	(5,807,000)	(5,377,000)	(5,479,000)	3,924,000
Other comprehensive income before reclassifications	368,000	(37,000)	40,000	278,000
Amounts reclassified from accumulated other comprehensive income			0	(9,616,000)
Other comprehensive income (loss)	368,000	(37,000)	40,000	(9,338,000)
Balance at end of period	(5,439,000)	(5,414,000)	(5,439,000)	(5,414,000)
Unrealized gain (loss) on available for sale securities
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	0	0	0	49,000
Other comprehensive income before reclassifications	(7,000)	0	(7,000)	0
Amounts reclassified from accumulated other comprehensive income			0	(49,000)
Other comprehensive income (loss)	(7,000)	0	(7,000)	(49,000)
Balance at end of period	$ (7,000)	$ 0	$ (7,000)	$ 0