Schedule of Cash Flow Hedges (Details) £ in Thousands, CAD in Thousands, $ in Thousands	Sep. 30, 2016 GBP (£)	Sep. 30, 2016 USD ($)	Sep. 30, 2016 CAD	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 GBP (£)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 CAD
Derivative
Derivative Asset, Noncurrent		$ 431
Derivative Liability, Current		212					$ 1,347
Derivative Liability, Noncurrent		2,414
Interest Rate Swap | US Dollar Notional Amount
Derivative
Derivative, Notional Amount		760,000					170,000
Derivative Asset, Noncurrent		431
Derivative Liability, Current		152					858
Derivative Liability, Noncurrent		2,414
Interest Rate Swap | US Dollar Notional Amount | 2016 Interest Rate Swaps
Derivative
Derivative, Notional Amount				$ 150,000	$ 440,000
Interest Rate Swap | Pound Sterling Notional Amount
Derivative
Derivative, Notional Amount | £	£ 50,000					£ 50,000
Derivative Liability, Current		60					465
Derivative Liability, Noncurrent		0
Interest Rate Swap | Canadian Dollar Notional Amount
Derivative
Derivative, Notional Amount | CAD			CAD 0					CAD 25,000
Derivative Liability, Current		0					$ 24
Derivative Liability, Noncurrent		$ 0