Segment Information (Entity-Wide Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Customer revenues	$ 399,358	$ 404,146	$ 377,794	$ 389,277	$ 403,351	$ 366,073	$ 334,576	$ 348,183	$ 1,570,575	$ 1,452,183	$ 892,345
Customer Revenues [Member]
Segment Reporting Information [Line Items]
Customer revenues									1,570,575	1,452,183	892,345
CAM [Member]
Segment Reporting Information [Line Items]
Customer revenues									308,661	285,276	228,956
CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
Customer revenues									205,047	168,106	156,516
All other [Member]
Segment Reporting Information [Line Items]
Customer revenues									334,300	314,014	286,579
All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
Customer revenues									$ 218,276	$ 205,934	$ 187,025