Debt (Details 2) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Line of Credit Facility
Covenant restriction, Maximum indebtedness to EBITDA	3.25 to 1
Covenant restriction, Minimum EBITDA to interest expense	3.50 to 1
JPMorgan Chase Bank, National Association
Line of Credit Facility
Amount outstanding	$ 45,000
Weighted average interest rate	1.86%
Expiration date	Jun. 30, 2020
Prudential Investment Management, Inc.
Line of Credit Facility
Amount outstanding	$ 0
Repayments of Long-term Debt	11,143
HSBC Bank (China) Company Limited, Shanghai Branch
Line of Credit Facility
Amount outstanding	0
Maximum borrowing capacity	$ 5,000