protected override decimal CalculateTransferedSum()
        {
            decimal incomeMoneySum  = CashTransferDocumentIncomeItems.Sum(x => x.IncomeMoney);
            decimal expenseMoneySum = CashTransferDocumentExpenseItems.Sum(x => x.ExpenseMoney);

            return(incomeMoneySum - expenseMoneySum);
        }
 public virtual void AddExpenseItem(Expense expense)
 {
     if (!CashTransferDocumentExpenseItems.Any(x => x.Expense.Id == expense.Id))
     {
         var newItem = new ExpenseCashTransferedItem {
             Expense  = expense,
             Document = this
         };
         ObservableCashTransferDocumentExpenseItems.Add(newItem);
         newItem.Expense.TransferedBy = newItem;
     }
 }