Reportable Segments and Geographic Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 577,264	$ 626,983	$ 535,103	$ 418,893	$ 560,421	$ 624,640	$ 558,301	$ 297,870	$ 2,158,243	$ 2,041,232	$ 1,387,344
Long-lived assets	587,397				599,474				587,397	599,474
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									1,961,303	1,869,874	1,242,305
Long-lived assets	566,028				580,868				566,028	580,868
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									171,175	171,358	145,039
Long-lived assets	20,689				18,472				20,689	18,472
Other Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									25,765	0	0
Long-lived assets	680				134				680	134
Total Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									196,940	171,358	$ 145,039
Long-lived assets	$ 21,369				$ 18,606				$ 21,369	$ 18,606