Fair Value Measurements (Schedule of Non-Recurring Losses Recognized Using Fair Value Measurements and the Carrying Value of any Assets and Liabilities Measured Using Fair Value Estimates) (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Assets, carrying value	$ 46,746	$ 31,264	$ 70,032
Assets, non-recurring losses	0	0	0
Vacant Owned Facilities
Assets
Assets, carrying value	2,496	2,537	3,863
Assets, non-recurring losses	0	0	0
Net Assets of Acquired Businesses
Assets
Assets, carrying value	44,250	28,727	66,169
Assets, non-recurring losses	$ 0	$ 0	$ 0