Acquisitions - Purchase Price (Details) - Progressive - USD ($) $ in Thousands		12 Months Ended
	Apr. 14, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Proceeds from long-term debt		$ 491,300
Cash Consideration	$ 185,454
Deferred Cash Consideration	29,106
Purchase Price	705,810
Senior Notes | Senior Unsecured Notes, 4.75% Note Due 2017
Business Acquisition [Line Items]
Proceeds from long-term debt	300,000
Senior Notes | Senior Unsecured Notes, 3.95% Due 2018
Business Acquisition [Line Items]
Proceeds from long-term debt	126,250
Line of Credit | Revolving Facility | Revolving Credit Agreement
Business Acquisition [Line Items]
Proceeds from long-term debt	$ 65,000