Annual report pursuant to Section 13 and 15(d)

Accumulated Other Comprehensive Income (Accumulated Other Comprehensive Income, Net of Related Tax Effects) (Details)

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Accumulated Other Comprehensive Income (Accumulated Other Comprehensive Income, Net of Related Tax Effects) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Accumulated other comprehensive income at beginning of period $ (8,887) $ (22,617) $ (20,836)
Other comprehensive income (loss) before reclassifications 5,209 15,660 (2,047)
Amounts reclassified from other comprehensive income 130 (1,930) 266
Net other comprehensive income (loss) during the period 5,339 13,730 (1,781)
Accumulated other comprehensive income at end of period (4,063) (8,887) (22,617)
Unrealized Holding Gains (Losses) on Available-For-Sale Securities [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Accumulated other comprehensive income at beginning of period (4) (4) (2)
Other comprehensive income (loss) before reclassifications (56) 0 (2)
Amounts reclassified from other comprehensive income 0 0 0
Net other comprehensive income (loss) during the period (56) 0 (2)
Accumulated other comprehensive income at end of period (60) (4) (4)
Unrealized Holding Gains (Losses) on Derivative Transactions [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Accumulated other comprehensive income at beginning of period (10,716) 6,773 6,087
Other comprehensive income (loss) before reclassifications 23,065 (15,559) 420
Amounts reclassified from other comprehensive income 130 (1,930) 266
Net other comprehensive income (loss) during the period 23,195 (17,489) 686
Accumulated other comprehensive income at end of period 11,964 (10,716) 6,773
Foreign Currency Translation Adjustment [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Accumulated other comprehensive income at beginning of period 1,833 (29,386) (26,921)
Other comprehensive income (loss) before reclassifications (17,800) 31,219 (2,465)
Amounts reclassified from other comprehensive income 0 0 0
Net other comprehensive income (loss) during the period (17,800) 31,219 (2,465)
Accumulated other comprehensive income at end of period (15,967) $ 1,833 $ (29,386)
Accounting Standards Update 2017-12 [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Accumulated other comprehensive income at end of period $ (515)