Investment in Joint Venture Investment in Joint Venture Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	51.00%
Payments to Acquire Interest in Joint Venture	$ 9,700,000	$ 6,900,000
Holmes Service Limited [Domain]
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	49.00%
Payments to Acquire Interest in Joint Venture	$ 9,300,000	6,600,000
Holme Service Limited [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Interest in Joint Venture	$ 9,300,000	$ 6,600,000