Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Roll forward of activity in insurance reserves
Balance at beginning of period	$ 39,111	$ 39,583	$ 38,850
Net increases in reserves	16,220us-gaap_LossContingencyAccrualProvision	16,861us-gaap_LossContingencyAccrualProvision	19,743us-gaap_LossContingencyAccrualProvision
Net payments made	(15,851)	(17,333)	(19,010)
Balance at end of period	$ 39,480	$ 39,111	$ 39,583

Amount of loss contingency liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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- Definition

Amount of payments made reducing loss contingency liability.

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- Definition

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

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