Debt Long Term Debt (Details) - USD ($)	5 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Jun. 30, 2015	May. 31, 2015	Dec. 31, 2014	Jun. 30, 2012
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 1,435,000,000	$ 1,435,000,000			$ 1,525,000,000
Add: Unamortized premium	5,376,000	5,376,000			5,824,000
Less: Short-term borrowings and current portion of long-term debt	0	0			(5,000,000)
Long-term debt (including related party)	1,440,376,000	1,440,376,000			1,525,824,000
$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 (1) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	80,000,000	$ 80,000,000			0
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 1.25%-1.75%
Line of Credit Facility, Maximum Borrowing Capacity	200,000,000	$ 200,000,000
7.375% Senior notes, due May 2018 (2) | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 0	$ 0			345,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.375%	7.375%	7.375%
6.625% Senior notes, due June 2021, $75 million related party | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 400,000,000	$ 400,000,000			400,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.625%	6.625%
Debt Instrument Face Amount Related Party	$ 75,000,000	$ 75,000,000
6.375% Senior notes, due October 2022 | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$ 525,000,000	$ 525,000,000			525,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.375%	6.375%
KOREA, REPUBLIC OF | $41 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due June 2016 (3) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.60%
Long-term Debt Including Related Party, Gross	$ 0	$ 0			0
Debt Instrument, Description of Variable Rate Basis		foreign currency funding-linked base rate plus 1.60%
Line of Credit Facility, Maximum Borrowing Capacity	$ 41,000,000	$ 41,000,000				$ 41,000,000
KOREA, REPUBLIC OF | Term loan, LIBOR plus 2.60%, due May 2018 (4) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.60%	2.60%
Long-term Debt Including Related Party, Gross	$ 100,000,000	$ 100,000,000			0
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 2.60%
KOREA, REPUBLIC OF | Term loan, LIBOR plus 2.70%, due December 2019 (5) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.70%
Long-term Debt Including Related Party, Gross	$ 70,000,000	$ 70,000,000			70,000,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 2.70%
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.55%, due May 2020 (6) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%	1.55%
Long-term Debt Including Related Party, Gross	$ 150,000,000	$ 150,000,000		$ 150,000,000	0
Debt Instrument, Description of Variable Rate Basis		foreign currency funding-linked base rate plus 1.55%
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.55%, due May 2020 (7) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%	1.55%
Long-term Debt Including Related Party, Gross	$ 80,000,000	$ 80,000,000		$ 80,000,000	0
Debt Instrument, Description of Variable Rate Basis		foreign currency funding-linked base rate plus 1.55%
KOREA, REPUBLIC OF | Term Loan, fund floating rate plus 1.60%, due June 2020 (8) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.60%	1.60%
Long-term Debt Including Related Party, Gross	$ 30,000,000	$ 30,000,000			0
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 1.60%
KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due June 2016 (9) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.70%
Long-term Debt Including Related Party, Gross	0	$ 0			70,000,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 3.70%
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.80%, due March 2017 (7) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.80%
Long-term Debt Including Related Party, Gross	0	$ 0			80,000,000
Debt Instrument, Description of Variable Rate Basis		foreign currency funding-linked base rate plus 1.80%
KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due July 2017 (9) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.70%
Long-term Debt Including Related Party, Gross	0	$ 0			30,000,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 3.70%
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.75%, due September 2017 (8) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.75%
Long-term Debt Including Related Party, Gross	$ 0	$ 0			$ 5,000,000
Debt Instrument, Description of Variable Rate Basis		foreign currency funding-linked base rate plus 1.75%
Minimum [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 (1) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.25%
Maximum [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 (1) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.75%