Subsequent Events (Details) - USD ($) shares in Thousands			12 Months Ended
	Jan. 11, 2019	Jan. 02, 2019	Dec. 31, 2018	Apr. 13, 2017
Subsequent Event [Line Items]
Maximum borrowing capacity				$ 400,000,000
Debt instrument term			15 years
Line of credit | Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity				$ 800,000,000
LTG
Subsequent Event [Line Items]
Percentage of ownership in acquiree			32.50%
Subsequent Event | Line of credit | Revolving Credit Facility | 364-day Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 250,000,000
Debt instrument term	364 days
Subsequent Event | Line of credit
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 1,650,000,000
Subsequent Event | Line of credit | 5-year Term Loan
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 250,000,000
Debt instrument term	5 years
Subsequent Event | Line of credit | 7-year Term Loan
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 250,000,000
Debt instrument term	7 years
Subsequent Event | Line of credit | Revolving Credit Facility | 5-year Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 900,000,000
Debt instrument term	5 years
Subsequent Event | LTG
Subsequent Event [Line Items]
Purchase price of acquisition		$ 324,000,000
Cash paid on acquisition		201,000,000
Initial working capital adjustment included in cash paid on acquisition		$ 33,000,000
Number of unregistered shares issued in acquisition (in shares)		4,100
Value of registered shares issued in acquisition		$ 123,000,000
Number of additional unregistered shares issued in acquisition (in shares)		280
Value of additional unregistered shares issued in acquisition		$ 370,000
Long-term debt assumed in acquisition		160,000,000
Line of credit borrowings assumed in acquisition		125,000,000
Acquisition transaction costs		$ 6,500,000