Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Apr. 30, 2017	Jan. 31, 2017	Apr. 30, 2016
Assets:
Total assets measured at fair value	$ 34,305	$ 32,530	$ 29,417
Liabilities:
Total liabilities measured at fair value	32,583	31,042	27,272
Level 1
Assets:
Total assets measured at fair value	34,100	32,385	28,698
Liabilities:
Total liabilities measured at fair value	34,421	30,831	27,073
Level 2
Assets:
Total assets measured at fair value	205	145	719
Liabilities:
Total liabilities measured at fair value	162	211	199
Other Current Assets | Available-for-sale securities
Assets:
Total assets measured at fair value	291	309	281
Other Current Assets | Short-term investment
Assets:
Total assets measured at fair value	147	154	159
Other Current Assets | Hedge derivatives-Assets
Assets:
Total assets measured at fair value	205	145	719
Other Current Assets | Level 1 | Available-for-sale securities
Assets:
Total assets measured at fair value	291	309	281
Other Current Assets | Level 1 | Short-term investment
Assets:
Total assets measured at fair value	147	154	159
Other Current Assets | Level 2 | Hedge derivatives-Assets
Assets:
Total assets measured at fair value	205	145	719
Other non-current assets | SERP assets - employer
Assets:
Total assets measured at fair value	1,241	1,091	1,185
Other non-current assets | SERP assets - employee
Assets:
Total assets measured at fair value	32,421	30,831	27,073
Other non-current assets | Level 1 | SERP assets - employer
Assets:
Total assets measured at fair value	1,241	1,091	1,185
Other non-current assets | Level 1 | SERP assets - employee
Assets:
Total assets measured at fair value	32,421	30,831	27,073
Other non-current liabilities | SERP liabilities - employee
Liabilities:
Total liabilities measured at fair value	32,421	30,831	27,073
Other non-current liabilities | Level 1 | SERP liabilities - employee
Liabilities:
Total liabilities measured at fair value	32,421	30,831	27,073
Accrued Liabilities | Hedge derivatives-Liabilities
Liabilities:
Total liabilities measured at fair value	162	211	199
Accrued Liabilities | Level 2 | Hedge derivatives-Liabilities
Liabilities:
Total liabilities measured at fair value	$ 162	$ 211	$ 199