Annual report pursuant to Section 13 and 15(d)

New Accounting Standards - Adjustment Disclosure (Details)

v3.8.0.1
New Accounting Standards - Adjustment Disclosure (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle      
Net cash provided by operating activities $ 116,062 $ 119,720 $ 44,715
Net cash used in investing activities (182,695) (1,929,680) (38,725)
Net cash provided by financing activities 68,944 1,861,433 (3,462)
Effect of exchange rate changes on cash and cash equivalents (6,858) (5,886) 0
Net change in cash and cash equivalents (4,547) 45,587 2,528
Cash and cash equivalents at beginning of period 70,742 25,155 22,627
Cash and cash equivalents at end of period 66,195 70,742 25,155
Accounting Standards Update 2016-18 [Member] | Pro Forma      
New Accounting Pronouncements or Change in Accounting Principle      
Net cash provided by operating activities 116,062 119,720  
Net cash used in investing activities (195,982) (1,915,345)  
Net cash provided by financing activities 68,944 1,861,433  
Effect of exchange rate changes on cash and cash equivalents (6,858) (5,886)  
Net change in cash, cash equivalents and restricted cash (17,834) 59,922  
Cash, cash equivalents and restricted cash at beginning of period 85,077 25,155  
Cash, cash equivalents and restricted cash at end of period $ 67,243 $ 85,077 $ 25,155