Derivative Financial Instruments - Summary of Derivative Positions (Details) - 3 months ended Mar. 31, 2017	GBP (£) $ / € € / £ $ / £	USD ($) $ / € € / £ $ / £
USD/EURO | Sell
Derivative [Line Items]
Notional Amount | $		$ 3,400,000
Weighted Average Remaining Maturity In Years	3 months
Average Exchange Rate | $ / €	1.07	1.07
USD/British Pound | Sell
Derivative [Line Items]
Notional Amount | £	£ 4,595,000
Weighted Average Remaining Maturity In Years	3 months
Average Exchange Rate | $ / £	1.26	1.26
EURO/British Pound | Sell
Derivative [Line Items]
Notional Amount | £	£ 5,700,000
Weighted Average Remaining Maturity In Years	3 months
Average Exchange Rate | € / £	0.85	0.85
Interest Rate Swaps
Derivative [Line Items]
Notional Amount | $		$ 242,812,500
Weighted Average Remaining Maturity In Years	3 years 7 months