Fair Value (Narrative) (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Fair Value [Line Items]
Notes payable, outstanding principal balance	$ 505,979,000	$ 543,332,000
Credit facility, outstanding principal balance	428,000,000	293,000,000
Contingent consideration obligations, fair value and carrying value	5,585,000	5,340,000
Contingent consideration obligations, maximum payout	8,450,000
Contingent consideration obligations, minimum payout	0
Fixed Rate [Member]
Fair Value [Line Items]
Notes payable, outstanding principal balance	129,665,000	131,233,000
Variable Rate Debt, Subject To Interest Rate Swap [Member]
Fair Value [Line Items]
Notes payable, outstanding principal balance	333,966,000	369,002,000
Credit facility, outstanding principal balance	210,000,000	55,000,000
Variable Rate [Member]
Fair Value [Line Items]
Notes payable, outstanding principal balance	42,348,000	43,097,000
Credit facility, outstanding principal balance	218,000,000	238,000,000
Significant Other Observable Inputs (Level 2) [Member] | Estimated Fair Value [Member] | Fixed Rate [Member]
Fair Value [Line Items]
Notes payable, fair value disclosure	133,197,000	131,984,000
Significant Other Observable Inputs (Level 2) [Member] | Estimated Fair Value [Member] | Variable Rate Debt, Subject To Interest Rate Swap [Member]
Fair Value [Line Items]
Notes payable, fair value disclosure	334,684,000	364,478,000
Credit facility, fair value disclosure	$ 200,230,000	$ 52,054,000