Derivative Financial Instruments (Details) £ in Millions, CAD in Millions, AUD in Millions, $ in Millions		3 Months Ended	12 Months Ended
	Jun. 29, 2016 USD ($)	Dec. 31, 2017 CAD	Dec. 31, 2016 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 AUD item	Dec. 31, 2017 CAD item	Dec. 31, 2017 GBP (£) item	Dec. 31, 2017 USD ($) item
Derivative [Line Items]
Number of contracts with credit risk related contingent features | item					0	0	0	0
Agreements terminated during the period, notional amount	$ 200.0
Weighted average fixed rate, terminated agreements	2.40%
Unrealized loss recognized upon termination	$ 4.9
Other Expense
Derivative [Line Items]
Loss on ineffectiveness				$ 0.4
Foreign Exchange Contract
Derivative [Line Items]
New agreements during the period, notional amount | CAD		CAD 9.5
Notional Amount | CAD						CAD 6.8
Foreign Currency Exchange Rate, Translation					1.29	1.29	1.29	1.29
2018 and 2019
Derivative [Line Items]
New agreements during the period, notional amount | £			£ 550.0
2018
Derivative [Line Items]
New agreements during the period, notional amount | £			250.0
2019
Derivative [Line Items]
New agreements during the period, notional amount | £			300.0
2020
Derivative [Line Items]
New agreements during the period, notional amount	$ 200.0
Weighted average fixed rate	2.52%
New agreements, initial notional amount, later increased | £			250.0
2022
Derivative [Line Items]
New agreements during the period, notional amount			£ 500.0	$ 400.0
Derivatives In Cash Flow Hedging Relationships [Member] | January 16, 2018 - December 31, 2018 | U.S.
Derivative [Line Items]
Weighted average fixed rate					1.88%	1.88%	1.88%	1.88%
Derivative liability, notional amount								$ 300.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2018 | U.S.
Derivative [Line Items]
Weighted average fixed rate					2.17%	2.17%	2.17%	2.17%
Derivative liability, notional amount								$ 1,150.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2018 | U.K
Derivative [Line Items]
Weighted average fixed rate					0.82%	0.82%	0.82%	0.82%
Derivative liability, notional amount | £							£ 550.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2019 | U.S.
Derivative [Line Items]
Weighted average fixed rate					2.06%	2.06%	2.06%	2.06%
Derivative liability, notional amount								$ 1,000.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2019 | U.K
Derivative [Line Items]
Weighted average fixed rate					0.90%	0.90%	0.90%	0.90%
Derivative liability, notional amount | £							£ 550.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2020 | U.S.
Derivative [Line Items]
Weighted average fixed rate					2.06%	2.06%	2.06%	2.06%
Derivative liability, notional amount								$ 1,000.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2020 | U.K
Derivative [Line Items]
Weighted average fixed rate					0.94%	0.94%	0.94%	0.94%
Derivative liability, notional amount | £							£ 500.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2021 | U.S.
Derivative [Line Items]
Weighted average fixed rate					1.46%	1.46%	1.46%	1.46%
Derivative liability, notional amount								$ 400.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2021 | U.K
Derivative [Line Items]
Weighted average fixed rate					0.94%	0.94%	0.94%	0.94%
Derivative liability, notional amount | £							£ 500.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2022 | U.S.
Derivative [Line Items]
Weighted average fixed rate					1.46%	1.46%	1.46%	1.46%
Derivative liability, notional amount								$ 400.0
Derivatives In Cash Flow Hedging Relationships [Member] | 2022 | U.K
Derivative [Line Items]
Weighted average fixed rate					0.94%	0.94%	0.94%	0.94%
Derivative liability, notional amount | £							£ 500.0
Derivatives In Cash Flow Hedging Relationships [Member] | January 1, 2018 - February 27, 2018 | Australia
Derivative [Line Items]
Notional Amount | AUD					AUD 135
Weighted average fixed rate					2.98%	2.98%	2.98%	2.98%
Derivatives In Cash Flow Hedging Relationships [Member] | February 28, 2018 - September 28, 2018 | Australia
Derivative [Line Items]
Notional Amount | AUD					AUD 85
Weighted average fixed rate					3.11%	3.11%	3.11%	3.11%
Derivatives In Cash Flow Hedging Relationships [Member] | September 29, 2018 - February 28, 2019 | Australia
Derivative [Line Items]
Notional Amount | AUD					AUD 35
Weighted average fixed rate					2.98%	2.98%	2.98%	2.98%