Acquisitions and Disposals - Allied Acquisition (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 8,000	$ 673,000	$ 0
Finite-lived Intangible Assets Acquired		28,948	315,000	18,500
Goodwill, acquired during period		$ 14,084	$ 807,381	$ 25,159
Allied International Holdings, Inc.
Business Acquisition [Line Items]
Cash consideration	$ 75,700
Contingent Consideration Measurement Period	3 years
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	$ 7,500
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	30,000
Business Combination, Contingent Consideration, Liability	15,000
Acquisition consideration	90,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	76,700
Indefinite-lived Intangible Assets Acquired	8,000
Finite-lived Intangible Assets Acquired	6,000
Goodwill, acquired during period	14,100
Insurance Segment | Allied International Holdings, Inc.
Business Acquisition [Line Items]
Goodwill, acquired during period	$ 14,100