Supplemental Operating Information (Tables)
 12 Months Ended
Dec. 31, 2014
Other Nonoperating Income (Expense) [Abstract]  
Schedule of Other Nonoperating Income (Expense) [Table Text Block]
Other nonoperating (expense) income, net, included in the statements of operations follows:
 
Year Ended December 31,
 
2014
 
2013
 
2012
Other nonoperating expense, net
$
(3,050
)
 
$
(2,827
)
 
$
(2,611
)