Hedging Transactions and Derivative Financial Instruments (Notional Values of Derivative Instruments) (Details)	Jun. 30, 2017 JPY (¥) T	Jun. 30, 2017 EUR (€) T	Jun. 30, 2017 USD ($) T	Jun. 30, 2017 KRW (₩) T
Contracts not designated as hedging instruments | KRW/USD | Foreign Exchange Forward
Derivative [Line Items]
Notional Values of Foreign Currency Derivatives | ₩				₩ 5,695,550,000
Contracts not designated as hedging instruments | JPY/EUR | Foreign Exchange Forward
Derivative [Line Items]
Notional Values of Foreign Currency Derivatives | ¥	¥ 266,000,000
Contracts not designated as hedging instruments | EUR/USD | Foreign Exchange Forward
Derivative [Line Items]
Notional Values of Foreign Currency Derivatives | €		€ 4,373,956
Contracts not designated as hedging instruments | EUR/HUF | Foreign Exchange Forward
Derivative [Line Items]
Notional Values of Foreign Currency Derivatives | €		€ 581,180
Contracts not designated as hedging instruments | USD/CNY | Foreign Exchange Forward
Derivative [Line Items]
Notional Values of Foreign Currency Derivatives | $			$ 6,083,500
Contracts designated as hedging instruments | July 2017 - September 2017
Derivative [Line Items]
Volume of Copper Derivatives	122	122	122	122
Contracts designated as hedging instruments | October 2017 - December 2017
Derivative [Line Items]
Volume of Copper Derivatives	122	122	122	122
Contracts designated as hedging instruments | January 2018 - March 2018
Derivative [Line Items]
Volume of Copper Derivatives	140	140	140	140
Contracts designated as hedging instruments | April 2018 - June 2018
Derivative [Line Items]
Volume of Copper Derivatives	98	98	98	98
Contracts designated as hedging instruments | July 2018 - September 2018
Derivative [Line Items]
Volume of Copper Derivatives	46	46	46	46