Aditya Birla Group firm Idea Cellular today reported a nearly 18 per cent dip in consolidated net profit to Rs 200.9 crore for the quarter ended December 31,2011,on account of higher depreciation and financing costs with respect to 3G investments. The company had registered a net profit of Rs 243 crore in the October-December quarter last year,Idea said in a filing to the BSE.