Summary of Significant Accounting Policies (Assets Measured at Fair Value on a Nonrecurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Loan receivable, impairment	$ 1,500	$ 1,500
Goodwill impairment charges		59,454	$ 0	$ 0
Total impairment charges		60,954
Level 1
Assets:
Goodwill	0	0
Loan receivable	0	0
Total assets measured at fair value on a nonrecurring basis	0	0
Level 2
Assets:
Goodwill	0	0
Loan receivable	0	0
Total assets measured at fair value on a nonrecurring basis	0	0
Level 3
Assets:
Goodwill	16,067	16,067
Loan receivable	13,000	13,000
Total assets measured at fair value on a nonrecurring basis	$ 29,067	$ 29,067