Debt (Interest Rates) (Details)	Dec. 31, 2016	Dec. 31, 2015
Subsidiary Term Loans [Member] | Term loan, LIBOR plus 2.60%, due May 2018 | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	3.49%	2.99%
Subsidiary Term Loans [Member] | Term loan, LIBOR plus 2.70%, due December 2019 | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	3.54%	3.02%
Subsidiary Term Loans [Member] | Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	3.58%	3.19%
Subsidiary Term Loans [Member] | Term loan, foreign currency funding-linked base rate plus 1.33%, due May 2020 | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	3.59%	3.19%
Subsidiary Term Loans [Member] | Term loan, fund floating rate plus 1.60%, due June 2020 (3) | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	2.79%	2.32%
Subsidiary Term Loans [Member] | Term loans, TIBOR plus 1.00% | JAPAN
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	0.00%	1.13%
Revolving Credit Facility [Member] | Line of Credit [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 (1)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	0.00%	2.13%
Revolving Credit Facility [Member] | Line of Credit [Member] | $100 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due June 2017 (2) | KOREA, REPUBLIC OF
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	0.00%	3.32%
Revolving Credit Facility [Member] | Line of Credit [Member] | Short-term term loans, variable rate (4) | JAPAN
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	0.32%	0.46%
Revolving Credit Facility [Member] | Line of Credit [Member] | Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) (5) | TAIWAN, PROVINCE OF CHINA
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	2.78%	1.66%