Summary of Significant Accounting Policies - Balance Sheet Impact of ASU 2016-02 Adoption (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Prepaid expenses and other current assets	$ 34,791	$ 35,454	$ 35,997
Total current assets	746,097	857,356	857,899
Operating lease right-of-use assets, net	36,613	39,110
Total assets	970,375	1,081,943	1,043,376
Liabilities [Abstract]
Other accrued liabilities	177,635	210,381	199,472
Total current liabilities	280,011	394,901	383,992
Non-current operating lease liabilities	31,514	33,823
Other non-current liabilities	7,800	6,067	12,232
Total liabilities	337,467	454,391	415,824
Total liabilities and stockholders’ equity	$ 970,375	1,081,943	$ 1,043,376
ASU 2016-02
ASSETS
Prepaid expenses and other current assets		(543)
Total current assets		(543)
Operating lease right-of-use assets, net		39,110
Total assets		38,567
Liabilities [Abstract]
Other accrued liabilities		10,909
Total current liabilities		10,909
Non-current operating lease liabilities		33,823
Other non-current liabilities		(6,165)
Total liabilities		38,567
Total liabilities and stockholders’ equity		$ 38,567