Derivative and Hedging Activities (Interest Rate Derivatives) (Details) ₩ in Thousands, $ in Thousands | 3 Months Ended | |
Mar. 31, 2018USD ($) | Mar. 31, 2018KRW (₩) |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 71.00% | 71.00% |
Consolidated Subsidiaries Interest Rate Swap 1 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 2.89% | 2.89% |
Derivative, Upper Range of Effective Rate, Variable Rate | 3.54% | 3.54% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 200,000 | |
Derivative, Fixed Interest Rate | 1.64% | 1.64% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.24% | 3.24% |
Derivative, Maturity Date | Feb. 1, 2019 | |
Unsecured Debt | $ 250,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 1 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 2 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 2.80% | 2.80% |
Derivative, Upper Range of Effective Rate, Variable Rate | 3.35% | 3.35% |
Primary Line of Credit Swapped Portion | $ 225,000 | |
Line of Credit Facility, Maximum Borrowing Capacity | $ 1,100,000 | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 175,000 | |
Derivative, Fixed Interest Rate | 1.65% | 1.65% |
Derivative, Basis Spread on Variable Rate | 1.45% | 1.45% |
Total Swapped Rate On Loan | 3.10% | 3.10% |
Derivative, Maturity Date | Feb. 1, 2019 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.15% | 1.15% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.70% | 1.70% |
Consolidated Subsidiaries Interest Rate Swap 2 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 3 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 2.89% | 2.89% |
Derivative, Upper Range of Effective Rate, Variable Rate | 3.54% | 3.54% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 100,000 | |
Derivative, Fixed Interest Rate | 1.64% | 1.64% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.24% | 3.24% |
Derivative, Maturity Date | Feb. 1, 2019 | |
Unsecured Debt | $ 250,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 3 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 3 Primary Line of Credit Swapped Portion [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 2.80% | 2.80% |
Derivative, Upper Range of Effective Rate, Variable Rate | 3.35% | 3.35% |
Primary Line of Credit Swapped Portion | $ 225,000 | |
Line of Credit Facility, Maximum Borrowing Capacity | $ 1,100,000 | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 100,000 | |
Derivative, Fixed Interest Rate | 1.64% | 1.64% |
Derivative, Basis Spread on Variable Rate | 1.45% | 1.45% |
Total Swapped Rate On Loan | 3.09% | 3.09% |
Derivative, Maturity Date | Feb. 1, 2019 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.15% | 1.15% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.70% | 1.70% |
Consolidated Subsidiaries Interest Rate Swap 3 Primary Line of Credit Swapped Portion [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 4 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 3.39% | 3.39% |
Derivative, Upper Range of Effective Rate, Variable Rate | 4.04% | 4.04% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 100,000 | |
Derivative, Fixed Interest Rate | 2.14% | 2.14% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.74% | 3.74% |
Derivative, Maturity Date | Feb. 1, 2022 | |
Unsecured Debt | $ 300,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 4 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 5 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 3.39% | 3.39% |
Derivative, Upper Range of Effective Rate, Variable Rate | 4.04% | 4.04% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 100,000 | |
Derivative, Fixed Interest Rate | 2.14% | 2.14% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.74% | 3.74% |
Derivative, Maturity Date | Feb. 1, 2022 | |
Unsecured Debt | $ 300,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 5 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 6 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 3.39% | 3.39% |
Derivative, Upper Range of Effective Rate, Variable Rate | 4.04% | 4.04% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 50,000 | |
Derivative, Fixed Interest Rate | 2.14% | 2.14% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.74% | 3.74% |
Derivative, Maturity Date | Feb. 1, 2022 | |
Unsecured Debt | $ 300,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 6 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 7 [Domain] | | |
Derivative [Line Items] | | |
Derivative, Lower Range of Effective Rate, Variable Rate | 3.39% | 3.39% |
Derivative, Upper Range of Effective Rate, Variable Rate | 4.04% | 4.04% |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 50,000 | |
Derivative, Fixed Interest Rate | 2.14% | 2.14% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.74% | 3.74% |
Derivative, Maturity Date | Feb. 1, 2022 | |
Unsecured Debt | $ 300,000 | |
Derivative, Lower Range of Basis Spread, Variable Rate | 1.25% | 1.25% |
Derivative, Higher Range of Basis Spread, Variable Rate | 1.90% | 1.90% |
Consolidated Subsidiaries Interest Rate Swap 7 [Domain] | London Interbank Offered Rate (LIBOR) [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Debt Instrument, Description of Variable Rate Basis | one-month LIBOR | |
Consolidated Subsidiaries Interest Rate Swap 8 [Domain] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | 100.00% |
Derivative, Notional Amount | $ 12,000 | |
Derivative, Fixed Interest Rate | 2.09% | 2.09% |
Derivative, Basis Spread on Variable Rate | 1.40% | 1.40% |
Total Swapped Rate On Loan | 3.49% | 3.49% |
Derivative, Maturity Date | Mar. 1, 2024 | |
Unconsolidated Joint Ventures Interest Rate Swap 1 [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 50.00% | 50.00% |
Derivative, Notional Amount | $ 129,590 | |
Derivative, Fixed Interest Rate | 2.40% | 2.40% |
Derivative, Basis Spread on Variable Rate | 1.70% | 1.70% |
Total Swapped Rate On Loan | 4.10% | 4.10% |
Derivative, Maturity Date | Apr. 1, 2018 | |
Unconsolidated Joint Ventures Interest Rate Swap 2 (Member) | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 50.00% | 50.00% |
Derivative, Notional Amount | $ 129,590 | |
Derivative, Fixed Interest Rate | 2.40% | 2.40% |
Derivative, Basis Spread on Variable Rate | 1.70% | 1.70% |
Total Swapped Rate On Loan | 4.10% | 4.10% |
Derivative, Maturity Date | Apr. 1, 2018 | |
Unconsolidated Joint Ventures Interest Rate Swap3 [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 50.10% | 50.10% |
Derivative, Notional Amount | $ 164,803 | |
Derivative, Fixed Interest Rate | 1.83% | 1.83% |
Derivative, Basis Spread on Variable Rate | 1.75% | 1.75% |
Total Swapped Rate On Loan | 3.58% | 3.58% |
Derivative, Maturity Date | Dec. 1, 2021 | |
Unconsolidated Joint Ventures Interest Rate Swap 4 [Member] | | |
Cash flow hedges of interest rate risk [Abstract] | | |
Noncontrolling Interest, Ownership Percentage by Parent | 34.30% | 34.30% |
Derivative, Notional Amount | $ 52,065 | ₩ 60,500,000 |
Derivative, Fixed Interest Rate | 1.52% | 1.52% |
Derivative, Basis Spread on Variable Rate | 1.60% | 1.60% |
Total Swapped Rate On Loan | 3.12% | 3.12% |
Derivative, Maturity Date | Sep. 1, 2020 | |
Swapped Foreign Currency Exchange Rate | 1,162 | |