|
Derivative Instruments and Hedging Activities Schedule of Derivative Instruments (Details)
In Thousands, unless otherwise specified |
Sep. 30, 2013
USD ($)
|
Dec. 31, 2012
USD ($)
|
Dec. 31, 2011
USD ($)
|
Sep. 30, 2013
Pound Sterling Notional Amount
GBP (£)
|
Sep. 30, 2013
Interest Rate Swap
US Dollar Notional Amount
USD ($)
|
Dec. 31, 2012
Interest Rate Swap
US Dollar Notional Amount
USD ($)
|
Sep. 30, 2013
Interest Rate Swap
Pound Sterling Notional Amount
USD ($)
|
Dec. 31, 2012
Interest Rate Swap
Pound Sterling Notional Amount
USD ($)
|
Dec. 31, 2012
Interest Rate Swap
Pound Sterling Notional Amount
GBP (£)
|
Sep. 30, 2013
Interest Rate Swap
Canadian Dollar Notional Amount
USD ($)
|
Sep. 30, 2013
Interest Rate Swap
Canadian Dollar Notional Amount
CAD
|
Dec. 31, 2012
Interest Rate Swap
Canadian Dollar Notional Amount
USD ($)
|
Dec. 31, 2012
Interest Rate Swap
Canadian Dollar Notional Amount
CAD
|
Sep. 30, 2013
Foreign Exchange Forward
Pound Sterling Notional Amount
USD ($)
|
Sep. 30, 2013
Foreign Exchange Forward
Pound Sterling Notional Amount
GBP (£)
|
Sep. 30, 2013
Foreign Exchange Forward
Euro Notional Amount
USD ($)
|
Sep. 30, 2013
Foreign Exchange Forward
Euro Notional Amount
EUR (€)
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Derivative [Line Items] | |||||||||||||||||
| Derivative, notional amount | £ 50,000 | $ 420,000 | $ 520,000 | £ 50,000 | 25,000 | 25,000 | £ 70,000 | € 149,976 | |||||||||
| Derivative assets, noncurrent | 52 | 52 | |||||||||||||||
| Derivative liabilities, current | 15,403 | 705 | 705 | 7,439 | 7,964 | ||||||||||||
| Derivative liabilities, noncurrent | $ 9,568 | $ 14,938 | $ 10,600 | $ 8,631 | $ 12,791 | $ 937 | $ 2,135 | $ 12 |