Summary of Significant Accounting Policies (Details 4)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Swedish Krona [Member]
Weighted average exchange rate for consolidated statements of operations
Weighted-average exchange rate for consolidated statements of operations	8.54	8.55	8.43
Japanese Yen [Member]
Weighted average exchange rate for consolidated statements of operations
Weighted-average exchange rate for consolidated statements of operations	112.15	108.75	121.03
South Korean Won [Member]
Weighted average exchange rate for consolidated statements of operations
Weighted-average exchange rate for consolidated statements of operations	1,128.65	1,157.14	1,130.22
Taiwan Dollar [Member]
Weighted average exchange rate for consolidated statements of operations
Weighted-average exchange rate for consolidated statements of operations	30.41	32.22	31.73